The Spy is an extremely strange class for an FPS in that it relies solely on strategy, trickery and deception, rather than brute force and skill in combat. The interesting thing about the Spy is success of a player playing this class relies near solely on their judgment of risks and skill OUTSIDE of combat, where the combat is simply a reward. As a Spy do not become frustrated when you cannot kill a player outright. The Spy is DESIGNED to need the advantage to succeed, hence emphasis leaves the ordinary fighting ability of the player. This means only a few players in Team Fortress 2 can use the Spy to good effect. So remember, a good Spy is a tricky Spy.

Before I start, remember, if you are going to learn to be a real team helping Spy, you WILL die plenty (hopefully for a large gain). That doesn't mean throw your life away for a kill, but we'll get to that later. If you are at the lower-intermediate level of the Spy, you will take a lot of deaths without the gain you hoped for. Don't worry about this, choosing the right time to stab is a learning process so to learn to not die, you may have to die more than once. This will help you know what doesn't work in a given situation, as you progress you will naturally find you know when to and not-to take action in a situation.

Lastly, the key to getting better is practice. There is no one set loadout or method to win as Spy, you will have to mix it up.

A quick and easy way to improve at Spy and TF2 in general is to adjust a few settings. These are ESSENTIAL.

Console

Start by opening your game and selecting 'Options -> Keyboard -> Advanced' and select both options if you haven't already. Return to the menu. Using the ~ key below escape, open up console.

Type in the following:

Code:

fov_desired 90

Fov_desired 90 allows you to see more through your screen. You'll see when you play.

Advanced Options

Click on the small 'Advanced Options' button next to options in the main menu and enable these.

> Enable fast weapon switch. (Fast weapon switch will skip the weapon selection menu and go straight to the next weapon along)

> Display damage done as text over your target.

> Play a hit sound every time you injure an enemy. (Don't use this if you use Pyro often, unless you want to have it automatically off with Pyro using scripts)

You may wish to deselect the following if you don't plan on using basic scripts, as it obstructs your view of the crosshair. There is an easy way to get around this:

> Automatically reload when not firing.

Other notable options:

Enable simple disguise menu - allows you to disguise with the buttons 1, 2, and 3, by first selecting a set of classes then the classes themselves.

Enable minimal HUD - Moves all HUD icons right down to the edge of the screen.

Draw viewmodels - Doesn't draw your weapons, meaning you can see more easily but can't easily identify the weapon you are holding. Some people use this, but I don't recommend it.

The 'Viewmodel fov' slider shows more of your weapon on-screen, which looks nicer on bigger screens with higher resolutions.

Basic Scripts

Because some classes require different settings than others, scripts help the player automatically adjust the settings to his liking depending on class.

Your script folder can be found here: 'C:\Program Files\Steam\steamapps\[your username]\team fortress 2\tf\cfg'

Go here and open up the .cfg for each class using notepad.

Scripts

NOTE: remember, it is always important when writing a script in one to write what you want in all of them, otherwise you may switch class to find you have that setting still activated when you want it off.

Auto reload

Because the Spy's reload is the only one that obstructs the crosshair, you may wish to have it on for every other class. In the Spy's folder, type the following:

Code:

cl_autoreload "0"

And in every other class, type:

Code:

cl_autoreload "1"

Hit notification

Many Pyros hate the hit sound. This can be turned on with:
Code:

tf_dingalingaling "1"

And off with:

Code:

tf_dingalingaling "0"

I recommend placing the "0" value in the Pyro folder, and placing "1" in every other.

Sensitivity

Scripts allow you to change the sensitivity for each class (changing it for weapons is far more complicated).

Code:

Sensitivity #

Replace the # with your desired sensitivity.
You will have to experiment with this command.

I won't be covering advanced scripts here, as these take a lot of testing and practice. If you want to do this find a scripting guide or Google some class specific scripts.

When I play Spy I like to operate on a general guideline of 3 enemy alertness levels: Green, Orange and Red. Learn to recognize them:

GREEN:

General team: This is when the opposing team members are fairly unaware of the presence of a Spy on your side, hence Spy-checking is rare and will only occur after a successful sap or stab.

Individual player: A GREEN player will not check you unless you are behaving suspicious. When playing they will be less alert, looking around them less often and having more of a tunnel vision, especially when chasing Spies. They will more often stand still to fire or heal and be slower to react to damage.

ORANGE:

General team: This corresponds with a fair awareness of a Spy. Engineers may check around and the opposing side will fairly attuned to the sound of your revolver and backstab. Enemy players will occasionally turn and look behind them, checking most who may be suspicious, but will not go out of their way to catch you. This is the closest to the "average" team.

Individual player: An ORANGE player will differ from GREEN player in that they will be less distracted by Spies and will look around more often.

RED:

General team: This means high alert. Pyros and Engineers will probably Spy-check frequently and most other members of the opposing side will be suspicious of everyone they encounter. A RED is not just a guy that shoots empty space. RED players do not turn their back to a team-mate until they fire or are otherwise verified. They will be more aware of what's around them.

Individual player: These are far more often the high level players. They will frequently turn around and be aware of the advantage they hold against you or you against them. They are less likely to be lured.


If you are relatively new to Spy and find yourself dying more often than killing, you are wasting your team's time and will be more efficient as another class. Try again later. ORANGE is o.k to be spy, but be cautious. GREEN is the all clear to go Spy and wreck havoc.

Most teams follow a general layout based on time:

Assuming no one has gone spy for a while and all is GREEN: Once you go Spy, the second you are killed someone knows there's a Spy. Die again and two people know. Sap and you're edging out of GREEN level.

GREEN will not shift into ORANGE until a few more stabs so you have a fairly large window, provided you are not detected on your walk to their base. To prevent early ORANGE changing make yourself known as little as possible, even during set-up time by using friendly disguises and cloaking into position.

A RED team will not eventuate often unless they are cramped, on defense or are generally more skilled. It usually takes more than one Spy, but on cramped maps just one can be sufficient.

Beware: the tactics employed to counter you may vary between teams. I have seen very effective Pyro-less anti-Spy teams.

Gaging Reactions

After playing on a server for a while you can come to recognise certain players for their skill as a player. These become a good gauge of alertness.

You can use these risk levels to assess the risk factor of a situation to determine if it is worth taking the stab. For me the alertness of my enemies completely effects the tactics I use.

You can learn to recognize even specific players who are newer to the game and more permanently GREEN simply by being unaware of how an advanced Spy such as yourself works. Observe distinctive players by class and actions who are repeatedly near you to gauge whether they will fall for your ruse.

Once you can recognize players' alertness, learn to act accordingly:

GREEN:

Disguise as one of your own team for the initial push to the enemy's base with your DR constantly out. No one will suspect you when you 'die' and you get to remain firmly in the GREEN zone. GREEN enemies heading towards you may not suspect you, so a Quick stab is more likely to work. When in this zone target Medics, as they will not be cautious and killing them will be most helpful to your team. They are also less attuned to your decloak sound.

ORANGE:

Orange players are your ordinary player, not so easily fooled but not bullet (or knife) proof. Don't expect them to always miss you decloak noise, but a small bit of distance should mean you are fine. When alertness begins to rise, cloak becomes more important over disguise, which will fool people less often.

RED:

Players are very attuned to your cloak noise, so keep your distance or use distractions. Only rely on your disguise for movement and when you area at a distance and there is little risk. If they come towards you consider yourself compromised, and start shooting/running. RED players don't often have to check everywhere because they are usually more alert. Attack when they are distracted.

Knife

The knife should be getting you almost all of your kills, but different play styles mean this can vary largely.

KNIFING TACTICS

Air strafing: Air strafing involves using your 'a' and 'd' keys while in mid air to direct your fall. To do this most effectively use your mouse to gently turn in the direction you are trying to go while holding only either your 'a' if you are turning left or the 'd' key if you are turning right. Alternate between each to get the most distance if required.

Aerial stab: The Aerial stab involves falling from above an enemy and landing behind them for a quick back-stab. This is a very effective technique if you can become skilled at it as there is little to no defense against it.
To pull off an Aerial stab, select your target from above (you don't have to be that high). Wait for them to take a predictable path of movement and leap down to land on or behind them. If they are more alert and are occasionally looking around, aim your jump to land on their head, so you can move in the correct direction at the last moment.

There are two methods of Aerial stabbing. Leap stabs and Drop stabs. For a Leap stab, generally the better option, you jump down towards their back, crouch and direct your flight by air strafing. Time your landing and direct your flight so that you always land slightly behind them and stab. Drop stabs are similar but you do not jump. This is faster but it affords less control and the advantage of comfortably jumping over their line of sight.

Stair stab (AKA Overhead stab): This involves approaching an enemy from the upper area of a stairway or slope, jumping over them while simultaneously turning, crouching and stabbing in a single fluid motion. The option to use this tactic doesn't come along often. Stair stabs are primarily used in self-defence because it can be risky if you have incorrectly gauged your target, but you can still deliberately bait enemies into this. Players rarely expect you to turn around and pull off this manoeuvre. When you do pull this off, however, it's important to be stabbing while still above them and making sure you are landing behind them to give them as little time to react as possible.

Gauging your target is important before performing a Stair stab. Use the knowledge you have learned from above to guess if they will expect it or not. As a general rule they will be less likely to fall for it the second time.

Your jump must be precisely timed. Firstly your must leap with the correct momentum and at the right time to allow you to land in the right place. Move closer and use less momentum if they are close behind you and vise versa if you are waiting for them. The former gives your target less time to react, but giving your stab length is easier to aim. More importantly, you must control your flight and land in the correct place. To do this accurately, you must use some very advanced airstrafing, which I will cover here: For the purposes of this example, say that to stab you turn around to the right... (just swap keys if you turn to the left). Jump SIDEWAYS, do not jump backwards. You are able to use your A or D keys to either speed up or slow down your jump. If you are still rising or at the peak of your jump and your target is directly below you, then you can use your D key to stop your flight VERY fast and almost head straight downwards as you turn to the right into their back. This works better at sharper inclines or from greater height. You can use both keys in the same jump to lengthen in as you fly over them, but slow it as you reach their back to make the stab for more likely to hit. You should only ever be holding A as you stab if you are at a VERY shallow angle or it is going to be close. Using these can nullify the effects of your target's movement or jumping with the wrong amount of momentum.

Blind stair stabs, preferable as your target will not be able to react as easily, are done using a corner by a stairway, jumping before they round it. It takes prediction.

A useful way to learn to do the above three tactics is to download a map called tr_walkway_rc2 and use the ramp there to practice Stair stabbing bots.

Quick stab: One of the easiest trick stabs. If an enemy heading towards/past you and is (even temporarily) in the GREEN zone it is immediately obvious, as they will be ignoring you. As you pass, quickly do a 180 and stab them in the back. Remember, the game won't give you your stab if you aren't quick enough to their back, better to go slightly too early than slightly too late, as, going forward, they will not notice you bump into their side for a fraction of a second.

Stalking: When using the the C&D or the IW, while cloaked, move up to a person and uncloak while following close behind them. Stab. You can stalk enemies that are chasing you using a quick cloak around them. This tactic can be risky as you run the chance of them hearing you uncloak. Take advantage of noise if you can.

Intercept: The act of watching an enemies movement and moving so your line of movement crosses directly behind theirs.

Knife

Your stock knife. Usually preferable for it's higher consistency, this is best used when you are unable to easily reach an enemy cloaked or if your enemies are very active.

Your Eternal Reward (YER)

Sacrifices the ability to disguise manually for an instantaneous disguise of your backstab victim. The backstab is silent.

I'd recommend this for an aggressive-defense style game-play. Playing the defensive team means the enemy is usually more clustered when making a push and there are less sentry encampments.

You will want to be looking for games where there are strong clusters but with the odd separated player for you to prey upon.

The great thing about this weapon is that you are able to make a string of back-stabs and still be hard to find, meaning targeting the right person first doesn't matter as much. For example, you won't have to risk trying to kill the Medic first, as he is far less likely to notice you after you have stabbed another player.
In saying this, there is a general advantage to targeting the faster classes first, allowing you to hunt down the slower classes more easily, and making it easier keep to the back of a crowd.

Forget the use of disguises for long term use, the disguise offers a short term but very useful way of blending in, silently and instantly, and makes it harder for the enemies to locate you after a stab. This should be the benefit you are focusing on.

Always exit a location cloaked, as you will not have any grace to get to your target's back before people behind him attack you. Leave a location cloaked and remain so until a certain distance remains between the two of you that upon uncloaking allows you to stab. Just before you uncloak, glance behind you to see who will see you stab. If it's too risky or an enemy is too close, pull out.

You need to kill someone quickly after uncloaking, so look for stationary or isolated enemies; even better are enemies already surrounded by your allies.

The nature of this weapon makes it perfect for targeting Snipers first.

Engineers can become an easier target here, more on that later.

Without a disguise, Sentries can be a difficulty, you can counter this by standing on top of them and uncloaking, moving side to force it to turn right around. Alternatively, you could circle around it, or wait for the Engineer to get close enough. The sentry will instantly ignore you once you stab.

Take advantage of the speed and silence of this weapon, enemies killed at the back of a group will not be noticed, meaning you do not have to continue attempting to kill as many enemies as you can and you can keep your alertness level low. This makes it good for attacking groups.

Unfortunately enemies like the Heavy, Soldier and the Medic (arguably the most Spy-targeted classes in the game) become less practical as the two former leave you slowed and the latter will mean your disguise is caught out very quickly. Be cautious.

If you encounter a Heavy-Medic pair, you are usually best off targeting the Medic first. Killing the Medic will mean he will think he has simply stopped being healed, leaving you to head off elsewhere completely inconspicuous. After killing the Medic, you can kill the Heavy if you want to, but you'll be slowed, so you might just want to leave him to your teammates, but, your current mindset should prevent you from getting too attached to your disguises.

Conniver's Kunai

Base health reduced to 60, gain the ability to steal your victim's health, stolen health can become over-heal (max 180).

This is the most aggressive knife in the game, you are able to save yourself from near death with a single backstab. You need to be constantly active and taking every stab you can find, as the health bonus will save you from their reactions. This might help people that can't help but carry on into death during chainstabs. If you aren't noticed by everyone in front of you, the efforts of those behind you can be nullified with ease.

Keep a constant eye on your health, because it will degenerate and you may find yourself engaging with far less heath than you had realised.

Try to avoid being seen at all before your first stab. Early combat is the complete antithesis for your success. Spam is another problem, if you can't find a way around, it will not work.

If you are discovered I highly recommend attempting to cloak and escape becomes your first priority, as your low health will lend you no aid in battle.

Backstabbing a Heavy, Soldier or Pyro gains you a large amount of health. Use this to your advantage by doing battle with your pistol if you want be able to make use of it soon.

Backstabbing people removes fire, making you more formidable to Pyros, if you have this equipped, worry less about the problems of a Pyro being nearby, since their anti-Spy effects can be nullified with a single backstab.

Like the YER, the Kunai can be used on Engineers effectivly because you are granted instant health to tank the damage from the sentry, enabling you to stab from further away. Stabbing and Engineer directly in front of a level three sentry still gives you time to cloak before dying, allowing you to re-disguise and sap.

Many people say the current bonus of this weapon doesn't justify such a low health, because the health you gain is often near that of the ordinary Spies base health. Your biggest weakness comes from your low health, if you are being caught often before stabbing, abandon this weapon for now. I do not recommend using it regularly, but your playstyle may suit it.

The Big Earner

+30% Cloak on kill for -25 max health.

Use of this watch means that killing someone and taking their weapon restores you to very high cloak, meaning this weapon favours staying cloaked more and being able to escape more easily.

This weapon synergises well with the Dead Ringer, as the protection of feigning death helps counter your low health, and stabbing gains you more of the cloak back, essential to your safe escape.

To start with I recommend you try every watch, as you will find different watches are better suited to different situations.

The Dead Ringer (DR) is useful for maps where players are spread out, but you have places where you can hide or with some flanking corridors.

The Cloak and Dagger (C&D) is better suited to open environments like when you need to pass areas that you can't reach in the open and might require waiting.

The Invisibility Watch (IW) is more useful if you are able to keep moving and there is a fair availability of ammo to restock.

I find that each watch has it's uses depending on your target, if you are targeting a sentry while on offense, the DR might get you caught out. If you are finding your way around the sides without the need for cloak, the DR might be beneficial. Try the DR if you haven't yet, as it enables you to remain active as a Spy and prevents long periods of waiting in corners for your cloak to recharge. All watches have their tactical validity, it's up to you to choose the one you prefer. Tactics in this guide require use of all kinds of watches.

You will need to become good at all watches, as you should be changing to suit the situation.

CLOAKING TACTICS

Use your cloak as soon as you are finished stabbing or when entering a new area, it is your main weapon next to your knife.

Invisibility Watch/Cloak and Dagger

Illusion: If you are spotted, retreat unpredictably while cloaked, even returning to their base is a valid tactic. Once an enemy looses sight of you, they usually assume you have continued in the same (or the obvious) direction. A good way to do this is to allow yourself to be seen cloaking in a certain direction, then change direction as soon as you are invisible. Use this every time you are being chased . DR users: after feigning death, quickly do a 180 and slip past them. If they are aware of your DR then they will continue on, trying to find you, if not: even better, slip past and get away to uncloak, be careful you aren't too noisy.

Baiting: Try to deliberately be seen cloaking around a corner by an enemy to draw them after you. You may wish to turn this into an Illusion by doubling back past them while invisible. You can use this to lead an enemy towards an allied rush or sentry, and also into a perfect location for you to stab. Pyros and Engineers are particularly susceptible to this in their over-eagerness to catch Spies, but careful if you are trying to double past them.

The C&D sacrifices some cloak and the ability to regenerate cloak with ammo or metal for the ability to regenerate cloak while invisible if stationary.

Both cloaks are great aids to the Spies arsenal, but you need to be careful you don't get caught in some bad habits. Avoid camping too long in the same place with the C&D, if no stab opportunity arises you are in the wrong spot. Move along. With the IW try not to get stuck hogging ammo your team may need, and don't get too caught up concerning yourself with not having full cloak ready. The large length means you probably won't need it and you could use the faster movement.

Conserve cloak. When traversing low-risk closed areas or corridors, temporarily remove your cloak and re-activate it just before exit. You may find the IW more suited to closed environments so you can take off your cloak regularly to do this.

If you are cloaked and see an enemy approaching you, retreat and hide untill they pass. Easy stab. Learn to time your uncloak correctly. Skill in prediction of movements is used here. I will cover that later, under "Reaching Your Target".

Cloak THEN disguise, vise-versa will leave a smoke trail. Uncloaking straight afterward prevents that small bit of smoke at the end showing, so your disguise is slightly and artificially faster.

When using the C&D, calculate how much cloak it will require to reach your target location, taking into account that you may have to dodge and the distance involved, and run at the appropriate speed to conserve cloak. Remember that ammo packs take the same amount of time to respawn as you cloak does to run out.

Beware of the noise uncloaking makes. If you discover a more sound-alert but vulnerable enemy such as a Sniper you have previously stabbed, retreat slightly before uncloaking.

Dead Ringer

The Dead Ringer sacrifices manual cloaking, replacing it with the ability to feign death upon hit (leaving you cloaked), a shorter cloak time, a very loud uncloaking sound, the inability to replace your DR until it has fully recharged, the lack of an outline when you are damaged while invisible and a far higher resistance to damage while cloaked.

I will usually run around with my DR up, only lowering in expectation of a stab or a shot.

Avoid the bad habit of becoming to scared to go anywhere without full cloak ready. For enough speed to be effective you will occasionally need to move with the higher risk of death.

Once enemies catch onto your use of this weapon, their alertness can rise unfavourably fast, meaning they will Spy-check and you will have trouble getting places. The best option if this happens is to simply switch back to your invisibility watches to throw them off.

The DR is designed to put emphasis on your disguise, so you have to be very skillful about what you disguise as. Pay close attention to the disguise tactics coming up later.

If a Pyro is following you to spy-check, remove your DR and try to briefly cross with the flame. Hopefully you will be out of range by the time he is following you. Activate the DR if you are out of range, or if you are stuck within range, find something to jump off and activate it in mid-air. If you can't escape, keep the DR up to minimize damage for as long as possible until you can find water, health or your own team.

Don't waste the DR's limited cloak, about a third of your cloak is used when uncloaking, so going past one-third cloak renders pulling out of your cloak early nearly useless. The further away the better. Only deactivate early if you are approaching ammo.

If an enemy is preparing to spy-check, remove your DR briefly and activate at about 3/4 to 1/2 health, long enough to be believable but short enough to retain heath. Leave it up if you are low.

Be careful about which revolver you chose, as they will suit different play styles. Make sure you read about and try all of them before making a decision. I am often torn on my favourite here.

This weapon is one of the most understated weapons in the game, dealing massive damage to unsuspecting players. Accuracy is more important with Spy than people think.

SHOOTING TACTICS

Always have 6 shots loaded. Make sure you reload whenever you get a spare moment.

Remember your revolver is very accurate, and can be used at large distances. Continually firing will leave you reasonably accurate at medium and close range, but you will need to wait between shots at long range.

If you fail a stab (unfortunately, it happens), usually the best idea is to either cloak out of there, or, if they are on low enough health, pull out your pistol and to try to take them out while running away, which is usually easy as they run in a straight line, not expecting you to turn around and fire. Here good accuracy with the Ambassador might be beneficial.

Is he on low health? Instead of a risky backstab, a shot with your pistol will finish him off easily. Use the health meter to pick off damaged targets. I can't emphasize this enough, your pistol is a near overpowered weapon that, in the right hands, can stop any over-eager, would-be Spy-hunter in his tracks. Equalizer wielding Soldiers are a prime target as they are likely to have low health and, expecting an easy kill, will not dodge.

Cool down: All three weapons are as precise as sniper rifles at the first shot, after that you must wait for a cooldown (just over 1 second) to fire as accurately as the first shot. The Ambassador's cooldown is merely visible, whereas the Revolver's is not.

Revolver (with a capital 'R')

More suited to defense and escape than the Ambassador.

This and the Ambassador are similar weapons, but if you find yourself revolver fighting without the chance to line up a head-shot more often then you will probably want to use this weapon for its consistency through higher firing rate and damage per shot.

Ambassador

Allows for head-shots, but has a lower firing speed and does 10% less damage.

This works like a long-range backstab, and so is more suited to range, assassination and calm moments than the other revolvers.

Although it may not feel it, the Ambassador is actually more accurate than the other revolvers at firing as fast as possible, due to the slower fire rate forcing you to let it cool down more.

How to line up a head-shot: This is mostly required for the Ambassador, but can be used for any revolver. Much like the Sniper, you have two methods of lining up your shot, tracking or waiting. Tracking is where you follow your target with your crosshair, keeping your movements smooth. Waiting means you hold your cross-hair still and wait for a strafing enemy to cross it. If you use the Ambassador, you will need to be good at both. A good way of tracking is to use your 'a' or 'd' keys to move your cross-hair left and right, which is best used if you are having some sort of distance showdown. If the enemy is higher on health and/or smart they will attempt to get close to you while strafing. If you think you're able to, you can try and track them while backpedaling, even using your strafing movement to do so if you can afford to slow down. If they are strafing, the best idea is to hold your cross-hair and wait for them to cross it. If you are using the revolver, you should be sufficiently good to hold the crosshair on their chest no matter what you or they are doing.

When using the Ambassador take your time with shots, even when retreating, waiting a bit for an accurate headshot will kill them quicker. This takes a lot of practice as it is hard to wait and be patient when you're hurrying to escape. The headshot is extremely powerful, dealing 102 damage, which will place eight of the classes in the red zone.

Use the health meters to decide if you need to headshot or bodyshot.

Use the Ambassador if you can headshot quickly during high pressure situations. you don't have to be the god of headshots to use it (bodyshots will still hurt), but skill at aiming is certainly preferable. Remember, the critical hit won't count unless your crosshair is at it's minimal size.

A headshot with this gun causes massive knock-back. If you can pull this off from below someone you can knock them a great distance.

Always go for the still target of you can, because you are guaranteed a lot of damage. Next best are targets heading towards you or are moving in a predictable fashion.

L'Etranger

Sacrifices damage for cloak regeneration upon a hit.

I'd only really use this if I was attempting the Saharan Spy, but if you don't use the pistol to kill then this might be your choice.

Your best tactic with this weapon is to make as many shots as possible. It's cloak regeneration means emphasis leaves killing at range and towards escaping and re-cloaking.

It's cloak regenerating effects make it most useful for use with the DR, as you can't cloak to escape once you have used it.

Use also aids the C&D, as you can't pick up metal to recharge your cloak.

If you are a fair distance away, waiting for your cloak to regenerate you might take a few shots to save time. Beware as this might raise your alertness level.

The Enforcer

+25% Damage done for a 0.5 second increase in time taken to cloak.

The Enforcer definitely works best with the Dead Ringer, as it's effects do not matter with it. I would only recommend regular use in conjunction with this.

The Enforcer has a very noticeable damage falloff, and favours close range combat.

Constantly change disguise, especially if you have been seen. Situation (i.e front or rear, target, etc) should dictate your disguise of choice.

You should be familiar with the importance of disguises so I will simply attempt to tune your understanding.

Disguises (in order of best to worst):

Engineer
Use this disguise if there are multiple engineers, as you are less likely to be caught out and have a reason to be near sentries. DO NOT use it to target individual engineers as you will be caught out when the engineer sees their own name on you. Also serves as fair general purpose disguise. With a small profile, he is less conspicuous. The speed of the Engineer disguise is equal to that of the Spy's.

My favorite tactic for waiting is the 'fumble-fingers' Engineer. If you are stuck uncloaked and are waiting for an opening, fake switch to your wrench, and stare down and in front of you, as if you were trying to use the PDA. Move about every now and again as if you were trying to position yourself.

Sniper
Also good general purpose, best for staying at the back of a group, other Snipers will generally not notice their own name on a person, due to their fixation to their scope. Speed of this disguise is also equal to that of the Spy's.


When waiting, you are best you pretend to be strafing about to wait for people to pass, because you can't scope, you need to have a reason not to be firing.

Spy
Use this in your own base or attempting to make it to their base. I have heard of people recommending against using this disguise as it naturally arouses suspicion, however, I haven't noticed the effect of seeing an allied Spy on enemies being particularly strong. I have put much of this down to misuse. Seeing a (supposedly allied) Spy behind your team or hanging around the back-lines or around an Engineer's buildings is extremely suspicious as a Spy doesn't usually have even a slightly plausible reason for being there, so you might like to be careful when using it. You shouldn't really be seen enough of this to have an effect anyway.

I have used this often when behind my own team's frontlines, pretending to be waiting for my team to give a good backstab. I simply wait for the enemy to push past. This is camping, which never really helps out your team, so use this only when there is little choice but to give your enemy false security.

Pyro
Fair disguise, great for front lines. The flamethrower can sometimes protrude around corners (so if I'm waiting for people to pass by I won't use this). Speed is also equal to the Spy's.

A good tactic is to occasionally walk around edges and corners to look as if you are Spy-checking but conserving ammo.

Demoman
Often become damaged and have to return to their base, making it a fair choice for during combat. The speed of this disguise is 90% of the Spy's, still fair, but you might like to use this more when your other disguises are wearing thin.

Try to pretend to be looking for locations to place stickey traps when you want to hang around.

Scout
The Scout's small size makes him inconspicuous, otherwise unbelievable for his 133% speed and habit of double-jumping. I have used scout while waiting in a corner for people to blithely stroll past.

Do not be seen moving much. Your speed will catch you out. Being in the air might help, but it will draw attention to you.

Medic
He is unnoticeably faster than the Spy. The Medic is good for baiting enemies into traps, and also provides a great excuse to be running after someone. This disguise is not good for sticking around like the Engineer's.

Unfortunately, the Medic is expected to be healing, so if you are being called for, you may want to fake weapon switch off your medigun pretend to BattleMedic. If you are following someone, holding your medigun will hopefully make people think you are trying to heal them.

Solder
Unexpected disguise as his speed is 80% of the Spy. I consider him near useless, as he is too slow and attention gaining.

Try to jump a bit if you are in front of combat, because many soldiers do this trying to get a good shot in. Soldiers also naturally call for Medics fairly often.

Heavy
Good for tricking GREEN medics to waste an uber. Although unexpected, mostly useless for anything.

Another good jumper, as many heavies jump around corners to charge in mid-air.

BLENDING/DISGUISE TACTICS

We all love that feeling the moment we notice that everyone in an area believes your disguise and you can roam and wait freely. Making this happen is always a mixture of alertness, luck and skill. Unfortunately, we can only control the skill and, to an extent, their alertness. You already know how to control their alertness, the best you can do is utilize all the skill you have to seem convincing.

Fake weapon changing is a good way to authenticate your disguise. Use "B" (default) to change the disguise's weapons slot to the one you are currently using. I.e. Holding the revolver and pressing "B" will make you appear to be holding your disguises primary weapon. Quick-switching between knife and revolver while pressing "B" continuously will make your disguise switch between his melee and his primary, making your disguise more convincing.

Fake reloading is another good way of appearing as an enemy. If you can, keep your pistol minus 1 bullet. When you are in the open or being watched pull out your revolver, fake weapon change and reload your weapon. You will appear to reload to the enemy. This provides a good excuse to retreat around a corner towards the enemy base (reload here) and wait for some enemies to pass for the back-stab. Your fake weapon reload will continue once your reload has completed or you switch weapons, so switching to do this repeatedly is a good tactic and provides a good excuse to be doing nothing. This tactic looks most convincing with the Pyro's and the Engineer's shotgun, as other disguises will only reload one projectile.

Remember when using your disguise that it is second to your watch. Against ORANGE or RED teams a disguise will only convince at a glance and only a small portion of their team will believe you for any longer than 5 seconds. Remember that you should be seen as absolutely little as possible. Unfortunately, there are times when being convincing as a disguise can be essential to your survival, whether you are seen before you can cloak, or you are out of cloak, you can't rely on the mere image to make you convincing, hence employing tactics seen here can be essential.

Your best and most basic tactic is to watch where you look. If you're not thinking what you might look like to the other team, you're doing it wrong. You'll want to watch the combat, with your enemies in on the edges of your screen. Use your peripheral vision when targeting enemies to help you appear as if you are not concerned with them. Pretend to ignore them. A teammate won't usually concern themselves with watching their buddies spine and waiting for them to turn around. Avoid eye contact.

Below are the approximate times you have before you are discovered while only using a disguise against the type of team you have observed. Remember, for the perfect opportunity, it takes a long as it takes.

GREEN: The risk comes from being bumped into by accident. You have a large window here. Assume you have about 20-30 seconds constantly in the presence of a single enemy.

ORANGE: The risk here come from enemies intentionally running through allies and the odd Spy check. If you give no reason to seem suspicious you can last about 15 seconds before you are caught out

RED : Do not to be seen for anything more than 5 seconds.

Make sure the above disguises make sense, Scouts don't run to their intel,
Engineers do, you don't see a Spy near a sentry and you don't see a Sniper pushing the front lines.

Stay calm! Blending in can be as simple as not reacting to the other team, even when shot at. Sometimes the enemy, seeing a lack of a reaction from you after Spy-checking, will assume you are friendly. Try looking away. Remember: when in Rome, do as the Romans would.

Dodge your own teams projectiles when you are visible. This tactic is used best when you are in front of one or two enemies and wish for them to continue past you without arising suspicion.

You look about 5 times more suspicious if you are facing away from the front lines when they are nearby. To counter this run backwards, glancing behind you briefly to see where you are going. If there are too many enemies blocking the way, you should attempt to blend in upon seeing them by continuing forward ahead of them and hiding when out of sight so you can again reach the back. If you have the DR just try to mingle towards the back. IW & C&D players: run around a corner, cloak to escape or get to the back. Alternatively you can deliberately bait them away, use this to weaken their forces by distracting a few of them. If you spot a Medic in the incoming group, then call for him, as not doing so would raise questions as to why you stopped retreating.

Allied disguises: Use this in your own base to add to your perceived force size and save cloak while you travel. Pyro is generally the best disguise as it wards off enemy Spies and makes them more cautious.

You might like to try using scripts to help you disguise faster. Beware though, these can be tough to perfect and require a bit of testing.

When near enemies, look with your eyes, not your mouse. An ally glancing around suspiciously starts ringing alarms. Depending on their alertness level, sometimes you might just have to resist the urge to look and instead continue on at the risk of being bumped into. If they are GREEN you can probably look around safely.

DO NOT call for a medic if you are spotted while disguised, as they can use the medic icon to find you through walls and when invisible.

You'll need to learn for yourself what works for you in a given situation.

As far as attack vs defense goes, much of your action will remain the same, with the only real differences involving the usages of Scouts, Snipers and Engineers and the levels/places of distraction.

The synergy with your pistol is not the same as between your watch and knife, so as far as the pistols are concerned, this really is personal preference, but if you are finding your requirements are changing from your pistols ability, you'll need to change.

Knife + IW - The default loadout, versatile and practical. Use if there is are hiding places placed behind the enemy you can uncloak in, and you won't need to wait in the open for long. Use if there's plenty of ammo.

Knife + C&D - Great for Engineer camping matches. Use if there is little ammo available or you are finding you need to wait in the open during a match. My preference to this comes from being able to uncloak in places more of my choosing, for example, using obstacles in the middle of battle, rather than behind it, because I won't be forced to uncloak, even if someone comes. This is considered better for defense.

Knife + DR - Use if players are becoming spaced out, and there are areas where you can move hidden from sight. This also makes good use of ammo drops.

Your Eternal Reward + IW - If you are going to use this, you will need a knowledge of the map and to know where you are going to hide. I would be cautious using this, as you will have to find a hiding spot, making it difficult to gain your first stab. Use this for an aggressive defense, where you can find ways around them.

Your Eternal Reward + C&D - Probably your best choice for YER, as you don't want to be caught in the open without your disguise. You will often need to wait before you can get your first disguise.

Your Eternal Reward + DR - If you're going to use this combination, you need to be able to hide well. I wouldn't recommend using this without the Familiar Fez. The advantage is that you can feign death and stalk them immediately, but their alertness level may rise fast. (Recommend the L'Etranger, for its cloak recharge, which you may need urgently)

Conniver's Kunai + IW - Use this if they are relatively unaware before you stab someone, but are in dangerous groupings that can deal damage well. This is my preferred watch for the Kunai, as the two's aggressive nature perfectly complement each other.

Conniver's Kunai + C&D - Since this watch allows you to hide closer to the enemy, using this may help counter your low health.

Conniver's Kunai + DR - The Dead Ringer's high ease of survival is commonly seen as a perfect counter to the Kunai's health nerf, but does not stack effectively with the high health after the stab.

Priorities

This list is for who you should look for first when you are ready to stab. This is not set in concrete, due to factors like Position, Risk, Alertness and Threat. These are all roughly equal in importance.

Position
The loner should usually come first, as you are far less likely to be noticed. Remember to watch that no one is behind you.

Go for the person at the back of the group, if they are too close to other enemies, their scream will be loud may alert their teammates before you can reach them. Although they likely won't hear the scream during combat, there is now a higher risk from them turning around while you are gunning for them or re-disguising.

Risk
There's always a factor of risk to take into account: being recognised by your disguise, being accidentally hit, running in to people.

This is why sometimes loners and spread out players can be more beneficial, however, clusters have their benefits, and can result in spectacular chain-stabs.

Generally I wont disguise as the class I'm targeting, as they are the ones that will usually see you.

Alertness
There's no point going for the medic if he has a RED zoned Pyro nearby.

If you can see the Medic is constantly turning around, while his target simply watches the doorway, you might just ignore the Medic and go straight for his target, using the doorway to escape. If you try your luck with the Medic, he will see you gun for him, call out and try to kill you, but if you don't even look interested, you might get a free stab.

Threat
The most important targets are the ones that are a threat to you or your team. Once, you stab, you will be exposed, so taking these out first can yield big rewards.

This means that sometimes the best choice isn't the biggest group. If there is a Heavy-Medic combo that is ruining your team? They should be the highest priority. Is there an Engineer's building that you should sap before your team pushes? The alertness levels here should play a part in your decision. If the Heavy/Medic is RED, you might just want to leave him and employ your skills elsewhere, possibly taking the risk of having them shoot at you.

Players topping the scoreboard are also good targets if you can locate them.

Target Classes (in order of importance)

All factors neutral, this is the order you should prioritize your hit selection on:

Medic
Killing their Medic is helping your team to no end. This can be a suicide run. Try waiting until he is distracted and not constantly turning around to heal others. Often you can continue on to hit his Heavy or Soldier if he has one.

If you've lost your disguise and missed your stab at the Medic, don't try to go for the Medic again, pick another target or escape.

If a Medic's buddy is RED, you don't need to go for the guy who is being healed, just wait for the Medic to fall back, hit him and retreat. Attempting to stab the Medic's buddy could lead to a very poor outcome for you.

Say you manage to bait a Medic into following you with his medi-gun. The problem is: do you attempt to stab the Medic or do you just carry on? The best thing you can do is use the voice command to say "No", and wait/hope for him to continue past you. Trying to stab him while he is healing you rarely works (unless you can draw him into a stair-stab), as they like to watch their targets. Otherwise, you can pretend to be returning to re-stock on ammo. If the Medic is close to you, try calling out "Spy!", if you're lucky he'll turn around. If you can't get rid of him without seeming suspicious, then you will have to continue on and later gain the satisfaction of embarrassing him when he gets an assist on his teammate after you make your kill.

Medics will rarely keep still. These guys become jumpy upon being Ubercharge ready. Medics are weak on their own, a good few shots with your revolver will take them down.

Engineer (defensive)
You should learn to analyze a situation and deem the best method to take against an Engineer.

Among other things, Engineers can camp behind their sentry (campers), abandon it (ditchers), move about the area around it (roamers), camp next to it or camp in a position that is nearby but not next to his sentry (usually upon a dispenser) (watchers). I will cover each below. All of these tactics are interchangeable, but I have named the most ideal.

Campers

The most common occurrence, this applies to Engineers that happen to be behind their sentry at the moment you choose to strike.

The stab-and-sap is certainly your best option here. Use quick-switch and get fast at selecting your sapper. Make sure the sentry is not facing you...

If you think it might be close you have 2 tactics:

1: The Circle Tactic: wait till the sentry faces the opposite direction you want to escape in, stab then run in the opposite direction the sentry will turn in to shoot you. You can do this for sentries that are in the open, by just running in the opposite direction they turn.

2: The Upgrade Tactic: wait for the Engineer to make the final hit to upgrade his sentry. Stab the second he hits it and use the time it's unable to fire to sap.

The alternative is to sap-and-stab, but you run a higher risk of the Engineer reacting sooner and turning.

If they camp against a corner or a dispenser, you might like to try to hop on top of them and stab from above.

Ditchers

These guys are usually actively Spy-checking or fighting. You have three choices.

1. Sap and run for a safe stab elsewhere, use with your teammates for best effect. This might be suited when there is a high risk from nearby enemies.

2. Sap and attempt to eliminate the Engineer before he reaches your sapper. You can try to stab him by waiting in a position that will leave you between him and his sentry when he returns (you might have to do this by Stalking). This might be best for areas that offer a place to hide. You can try shooting him. You can even use his own buildings as cover. This is best used against close but out of sight Engineers, where you have the element of surprise.

3. Sap and shoot his stuff with your revolver. This will work better if he has gone but will be close enough break your sapper before it destroys everything.

Choose your option carefully, taking into account the engineers distance and his alertness level.

If you can find a place to hide, you might want to try to pick off the Engineer's buildings from a distance with your revolver. This is especially effective if the area is being watched by a Pyro or Engineer or the area is too crowded to traverse.

Roamers

Often Engineers leaving the direct proximity of their sentry will be attempting to get metal or check for Spies. You can capitalise on this by waiting in an area that is just out of sight of the sentry and striking from the safety of cover. You might find you have to wait around the area, and move to where the sentry can't see you once the Engineer leaves.

You can also wait for him to leave and treat them like a ditcher.

Watchers

If they camp even a small distance from their own sentry, use your revolver from cover to kill the Engineer. This can be risky if you are seen by an opposing team member. Be quick and careful. Otherwise you are better to sap and run.

Level 1 and 2 sentries allow you to stab then sap even if it is facing you as long as you are on full health. Level 3 sentries need to be facing away so you can circle away from them.

A great tactic for all four of these situations (but best for when you have little choice) is to sap and then shoot the Engineer before he can knock off your sapper. This requires good accuracy, but is great for hard-to-stab Engineers.

If your team is pushing, you can continually replace sappers as the Engineer knocks them off, rendering it useless and vulnerable. You are best to do this while your team is attempting to take it down and the Engineer constantly repairing.

If you are unable to cloak after sapping, disguise as the Engineer and pretend to be trying to find a Spy. Call out "SPY!" to authenticate yourself.

Sneaky teleporter tactic: If you know there is an enemy Engineer at the other side of his teleporter, sap it then wait on top of it for him to repair it. Hopefully you'll get a telefrag when he repairs it and you can sap as you will.

Try sapping as an enemy or group of enemies pass by. The Engineer may try to Spy-check them and miss you, providing the opportunity for escape or a backstab.

You can bait an Engineer from his buildings by deliberately being seen cloaking around a corner. Double back and sap his stuff.

Don't forget that Engineer's dispensers will heal you. Use this to your advantage. If you are awaiting the Engineer's return, you might like to replenish your health before sapping the dispenser too. This works when cloaked without showing the line to your body.

Sniper (isolated)
The Sniper is usually isolated, making him a prime target. Remember running and jumping does not effect accuracy, so running towards a Razorback (or even a normal sniper if you like) while lining up a headshot with the Ambassador (or simply attacking with the other two revolvers) is an efficient way of taking out Snipers. Snipers are easiest to hit with any weapon when they scope because they slow right down, so make sure you take the chance to strike when they do this.
If you are waiting to backstab an alert Sniper, uncloak as soon as they scope to maximize your time.

More experienced Snipers will rely on head-shots and rarely stay scoped for long. ORANGE or RED Snipers occasionally Spy-check around them. Upon completion of a kill in a risky area, they will always attempt to retreat and restock.

Heavy
Easy targets for their 77% speed. Wait until they are distracted.

When they find themselves without support and close to enemies, they will be quick to turn around and run.

Pyro (GREEN)
If they become aware of you their flamethrower will quickly burn you to a crisp, so you might like to target these guys while they are unaware. When overwhelmed, due to their short range, they try to run around the nearest obstacle or corner where people are forced into their range. Go crazy looking for Spies upon discovery, but will usually follow the most obvious route. Once you kill them, they may get a little mad at such embarrassment, and quickly turn ORANGE.

If you know one is nearby, or have killed one, avoid hiding in the same or predictable place, as they may just decide to check if you haven't moved.

These guys are cautious when they are out of range of an enemy, preferring to keep out of open areas. They can be surprisingly unalert, as they never suspect Spies to target them.

Soldier
Good slow target with high firepower. Watch for rocket-jumpers, if they are in the open avoid soldiers with Gunboats.

Are very careful with defending their own Medic. These are one of the best classes to target because they become very distracted during combat. When endangered, they will usually pull out their equalizer and either run for it or make a last stand, if you are safely hidden, a good shot with your revolver will stop them.

Demoman
Good choice to kill as they are usually guarding stickies, meaning stabbing him lets your team advance. These guys don't like stopping for very long.

Charge'n'Targe Demomen are great targets to combat because they may have trouble hitting you with the Grenade Launcher's inconsistency. Be sure to use obstacles and corners to prevent him charging you.

Engineer (offensive/Gunslinger)
Their sentries are an annoyance for your whole team, however a lower priority as their threat themselves is minimal. Sap as soon as you see that mini-sentry go up.

These guys can be more difficult, as they are less distracted by their gear than defensive Engineers. Once they have planted their sentry they will usually run for the nearest exit.

Spy
The best thing you can do against this class is spot his disguises when he's in his base and let your team know. Most of the time you might as well ignore him. The biggest danger with these guys comes from accidentally running into one in the battlefield while cloaked. If you are around your own team, keep trying to be in their way, otherwise pull out fast.

Remember when being chased that they are only effective close range and are otherwise easily put down with your revolver.

Sniper (offensive)
Not as effective Spy hunters as scouts or Pyros, meaning they can be safely ignored here. Watch out for Jarate, as this makes them a huge threat to your ability to escape.

Scout
Too fast, but are possible to kill. Better to target groups that don't have scouts, as they hunt you down very efficiently. Scouts rarely keep still, but sometimes can accidentally backpedal into you. When they are overwhelmed they simply turn and retreat. Provided they are not being shot at, their line will be straight, making for an easy Quick stab.

Pyro (ORANGE/RED)
Pyros in their ORANGE and RED zones are very hard to kill. Stay away if you can. Once again, a group without this class amongst it can be considered a far lower (even minimal) risk. If you do target a group with one of these guys, you might like to wait until he is distracted and target him first. Other than that, don't bother, as they often decide to turn around for a quick check. Never stalk or try to catch up with these guys. If they're gone they're gone. Upon seeing an ally they will Spy-check.

Moving While Undetected

The single largest gap in advanced players technique is their awareness of what is occurring around them. Start by focusing on always looking around you, then focusing on using every moment to peek around to get a good idea of where the enemy is. At all times you should know who is around you.

Now that you have learnt how to select your target, we get to the business of reaching your kill. We will start with getting to the back.

Start by using your cloak to survey the situation first.

Some crowds are just too thick or full of spam to go through. Don't be stupid and think you are skilled enough, because you're simply swapping skill for luck. Change class or go around.

Use the distractions your teammates create to get behind them. If there is none and they are already alert, you can make one yourself. If a more alert enemy, like a Pyro or a Medic, sees you and abandons their post to chase you, you can cloak and pass them to hit their now vulnerable teammates. Be cautious to only do this in the open.

This may sound crazy, but try playing as other classes to learn their habits. Knowledge of the habits and favorite tracks/positions of a class is extremely important for prediction of the next move of that class. A analyzed knowledge of the play style of each class (or even players if you are targeting specific classes) can be applied to many situations to gain you your next kill.

All players have similar mental processes when in game. Enemy's decisions to move forward and retreat can become predictable based upon the situation they are in. Things such as player numbers and counter-classes can lead to varying rections. Most often it is as simple as push/retreat.

If you are near their spawn, pay attention to who is dying at the time. This can warn you of a rush of enemies soon to come and give you time to position yourself. It also allows you to make decisions based on how many enemies will be coming up, if no one has died recently then it is safer to pick off stragglers.

You have two different methods of movement, safe and efficient:

Safe

Safe movement is preferable when you are unsure where the enemy is or there are multiple enemies, for example blind corners or well-used pathways.

To do this, jump onto obstacles and only be in the middle of a pathway to change sides. If there is only one path then try go where the enemy wouldn't, this means using areas that are usually easier to just walk around and taking blind corners wide.

Generally the sides of the path are safer, but be careful your hiding spot isn't a common favourite for Spy-checkers.

Efficient

Efficient movement is better when you are aware of the enemies location, or when you need to catch up to a player.

Efficient movement can effectively make you move faster than the average player. To do this, take as many shortcuts as possible. Every bit counts. You can usually figure out what turn they're going to take or what way they're heading, take a more efficient route. Be ready for them to turn the corner and try to get in a position that makes them walk past you, allowing you to Intercept them. Jump over gaps and up onto ledges instead of going around them, practice doing this in every class to get into the habit.

You can use this to conserve cloak, too. Taking corners as narrow as possible is a great way of doing this.

Always remember to take a mental note of everything there, including enemy position and advantageous terrain.

Avoid calling for a medic in a crowd and drawing attention to yourself. Only do so if you are about to leave to bait him out of safety, or if your disguise is on low health and you have a good reason to be retreating.

Awesome, you're at the back. Now it's time to unleash hell in a looping chain of backstabbing death.

Many Spies may find themselves forced to camp for a fair amount of time before they think it's a good time to uncloak. If you can, avoid waiting in the same spot for the uncloak. This is usually caused by either an overly active group or a player that continually looks around. Either you move out of sight and uncloak or you move off to find another area. A good tactic for crowds with people looking around is to wait for them to all be turned away and uncloak then for your best chance, but usually I leave to uncloak. This is because seeing an uncloak during action causes people to focus on you because you are a massive and definite threat with low health. Seeing a possible teammate Spy join the fray from the back isn't worth Spy-checking during high action.

If you you are aware of alertness, you will know the noise from your watch may tip off some of the more experienced players to your presence. Because of this, you have two approaches: 1) Wait for a sound, for example the domination or attack sounds. 2) Uncloak from a distance.

It's inevitable that sometimes you will be seen uncloaking. If you are closer to your target than they are to engage you, then you are best to gun it for them, if they can reach you before you reach your target you need to re-cloak as fast as possible, because they will attempt to give chase. If they aren't distracted with combat you will need to be good with Illusions.

In general, it is better to be as close as you can be to someone when you uncloak, taking risk into account. Avoid running too far back to uncloak and try to find closer obstacles to uncloak behind. This is another reason height is prefered.

You need to exercise caution when uncloaking. You have two options for uncloaking behind the enemy: 1) Wait, hidden until you are fully uncloaked to chase a target while trying to blend in, for reference's sake we'll call this run-and-stab. 2) You move out of hiding while cloaked and uncloak in the open. We'll call this the cloak-and-stab. The cloak-and-stab is typically seen as taking the shorter, higher, risk over the longer, lower, risk. Unfortunately the risk is never as black & white as that. The choice is yours.

Run-and-stab

This is the most commonly used option, because most of the combat is done in disorganised crowds (where this tactic is best) and it is safer to uncloak from cover.

The best idea is to wait for the last person, however, if you try to target someone with people behind him, and use the run-and-stab, accompanied by every disguise tactic you can think of.

If there is high action, or a defensive position behind you, the run-and-stab will be suitable, as the action may cause you to uncloak at the wrong time. The risk of being seen from behind is higher, meaning if you uncloak a little too soon or late, you will be toast. This is better for larger crowds, because you can easily be lost in the bustle.

You see a solo target coming and they are unaware of you, you can hide, uncloak and time your exit to meet his back.

Cloak-and-stab

This works better with YER, as you can't risk being seen as much.

Remember to time your uncloak to meet their back as soon as you are able to stab.

Generally the more risky, as being seen once means instant death. Use if the risk of being seen is greater than the small window of decloak, such as in more open areas where you cannot use obstacles. If there are people behind your target, depending on alertness, use the cloak-and-stab, because they may decide to Spy-check you if you cloak-and-run. In general it is not considered prudent attempt that kind of stab where they are close enough to kill you anyway.

If Spy-checking is underway, then you will want to use the cloak-and-stab. This also allows you to pull out if you realise the stab will be to hard or people approach from behind, leaving you fully able to wait and target them. The run-and-stab leaves you with little other option but to continue and pray you blend in.

Use this advantage of extra stealth to check around and behind you for potential threats upon uncloak. If there are people behind you, you have the option of pulling out before committing yourself. If a person is behind you, you can still uncloak as long as you believe you can make a clean stab before they can harm you. If there are a large number of enemies passing by, you can wait for a lull before cloaking and moving out behind the last person. Glance behind and uncloak if it's safe or wait for the next enemy to pass if someone comes.

The cloak-and-stab should be reserved for more predictable enemies who are not likely to move at the wrong moment, such as certain players you may have observed to be either RED or ORANGE. Uncloak sooner if they are near combat and less predictable.

The key to catching up with a player (especially Medics, as they are great targets but are faster that you) is efficient movement. Use all of the tactics you have learnt about efficient running to catch your prey.

When running efficiently, you may have to make compromises. For example, enemies likely movements or the dreaded blind corner. Unless in a hurry, take wider corners with room to spare, and wait by narrow ones for sounds like footsteps or, if you're near their spawn, the sound of the doors opening.

Prediction: Learning to predict and accurately guess the next movements of an enemy is essential for the Spy to learn. To do this you need to be able to put yourselves in their situation, and work based on how you would react. You'd be surprised at how everybody is the same in this sense, with the same survival instincts. You'll find later on that you can memorise the most common actions taken for the most common situations, and planning for their actions can become easy. This doesn't happen in a day though. Actively practice this while gaming, use this to anticipate before you leap into your stab. Unfortunately, not everyone will act as you had planned and people may appear in places that you hadn't anticipated, this is normal, you're not a god and you can't always know when a Pyro will appear. This isn't your fault, just remember: nothing is ever guaranteed. When you are in a busy area, you need to use your eyes. Watch enemy movements, learning to predict what they will do next is an important skill to learn. This also helps for reaching the back.

Practice trying to predict your enemies movements and intercepting them. For example: if you know they are heading towards a rush or a sentry, chances are they will backpedal. Be ready for them. If they are low on health or have just completed a kill they will probably move to the nearest exit next. Move to intercept. If you are above them be ready for an Aerial stab. If you see a Heavy-Medic pair chances are at some point they will both be distracted with an enemy.

Higher skilled enemies may deliberately move unpredictably during combat. This makes for a hard stab. Stay near the back and keep your eyes open for on enemy to present their back to you.

People always have this bad habit of focusing solely on their target and forgetting to watch around them. Target these people, as they will not notice you approaching them. When busy in combat, enemies become distracted, making for an easier stab. Remember about prediction, if they about to attack an enemy they are an easy target for you.
The advantage to people who are focusing on one area is that you can easily abuse the limited field of view of the player. Because all players will have an FOV of 90 degrees or less, you can approach from the side and even slightly more forward that that and they will still not see you. When you come in from a closer angle, be sure to take note of where else they are likely to look, for example alternate areas where combat may occur or escape routes.

When you are at the back and there is a lot of movement, don't feel hurried to stab. Unless enemies are behind you, you can move about the rear, continually readjusting your movement to intercept until the time is right. A hurried stab will create problems and missed opportunities. Too much patience, however, could lead to your discovery, or you may miss a fleeting vulnerability. Sometimes you will have to wait for that perfect opportunity. The amount of time you can assume you have before you are (somehow) caught depends on your skill here and the enemies alertness level, so judge your own skill critically. Avoid the senseless bravado in those chaotic situations. If you can't make a clean stab, don't attempt it.

If an enemy is clearly strafing backwards in one general direction you can more easily move to intercept them instead of moving straight towards them.

Speedy reactions are important for the Spy. People can change direction unpredictably. When you are lining up an active enemy, you will have to continually reposition yourself so that you will intercept; this can be very difficult to master, give it time, you will eventually learn how people move.
If you are targeting one of these enemies, you will need to use your skills of prediction to figure out where they will next turn. This is usually towards the next enemy, exit or Medic. To avoid being seen by this actively turning enemy, you'll need to dodge his line of sight by moving in a wide arc away from where you will think he will turn before you can stab or escape.
No Spy can perfectly predict the movements of skilled enemies when they are moving very unpredictably. The likelihood of them turning around as you attempt a stab is far too high, meaning you will likely be caught out before you can make a stab. The best stabbing opportunity is when they are distracted.

Vertical is better than horizontal. People rarely look up so whenever possible you should seek a vantage point up high, either to sneak around, get away or to bring down death from above...
This is why performing Aerial stabs are the best (and the most satisfying) way to kill an enemy, as there is no way for the enemy to see you coming or prevent you from stabbing them. Even if you miss, you are more easily able to pull out/try again before you are spotted/caught.

It's important, in those few seconds when you are exposed to reach your target, to become effective a blending as possible. Use your disguise tactics.
Never look at the person you are about to stab if you are visible to enemies, you don't even have to run straight towards them initially, because if anyone turns around (or is behind you) they will see a supposed ally blatantly stalking their teammate. Instead, pretend to be interested in the combat. Look away and strafe to them, if I am behind them I might pretend to be watching their flanks. You can satisfy your urge to stare at your target by pulling your eyes off your cross-hair and watching a point nearer to the edge of your monitor and keeping them there.

It's a good idea to go in with a plan or a general idea of your next few actions, but be ready to change it at any moment. If a target starts Spy-checking or moves off you will need to pull out or (depending on situation, distance and time) change target quickly. A good Spy's movements are always carefully calculated.

Choose your stab location carefully. An open or hidden spot enables you to escape where witnesses will have difficulty shooting you and be unable to find your next direction.

Crouching targets allow you to jump over them, meaning no matter the direction they can be targeted easily. Try blend in and when you are close enough, jump and crouch over them.

Remember that people can still be unpredictable. If they face the wrong way, pull out while you still can. Don't go in for a panicked stab, because this will only get you killed.

Read this. You need to understand the mechanics of the Spy's backstab: http://technofovea.com/blog/archives/278

Be aware of the distance and angle required for a back-stab. You must be behind them, within melee range, and facing them. If you are above them, crouch, because melee comes from your head and you need to be in range (which is extremely short). Line up yourself with their gun's direction, never their shoulders.

Because your target can move at the last second, remain alert to make fast changes to your movement.

You need to be prepared to move with your target, adjusting your direction in accordance with theirs.

If you land a successful stab and there are other enemies nearby, depending on distance you might want to pull out and cloak instead of going for them, as they may have seen or heard you. Getting away fast is important if you land amongst enemies.

If your stab is at the back of the crowd, you are sometimes better to pull back a bit and find another player at the back, instead of simply charging forward, because they are less likely to be noticed, so you can always start another chain-stab from a different part of the back.

Often what makes a good Spy is the ability to escape when he is discovered, as you can continue on after escaping to gain another kill, instead of waiting to re-spawn. A good Spy will be tricky, able to play mind games with his enemies and never seeming to be where they think he is. When you make your stab the key is to get away quickly before you are chased down by his teammates.

Remember this always when playing Spy: The Spy is a hit-and-run class (keep it in your head while you are playing). Make your kill(s) and get out of there FAST, never linger for the combat unless it's to finish of a damaged enemy. The key to Spy is being able to disappear in an instant. Always cloak the second a stab or sap is done unless you plan on hitting another nearby enemy or you are SURE no-one else is around to see you, tactics 2 and 3 (seen below) might even come after this.

You have just completed all available backstabs for a run. Now you have three options: 1) You cloak straight away and retreat unpredictably, 2) you pull out your revolver and fire as you attempt to escape or 3) you attempt to make a last stand/do battle. You should be able to tell when you are out-gunned enough to warrant use of each of these.

1) This is your best and default option and you should do this most of the time. Especially if you are unsure, the best idea is to simply bail out by cloaking and running to return later. Attempting to kill them after failing a backstab will raise their alertness and will likely result in your death. When you cloak, it is important you use your eyes. You can see where they're moving! Predict their movements and avoid them. This tactic will not work with a Pyro nearby, but you shouldn't have attempted that stab in this case, unless it was a Medic.

Straight after a back-stab, quickly cloak and manoeuvre unpredictably, use obstacles and avoid the obvious course of action.

2) If you are being chased, the only survivor is low on health or the outlook on escaping looks bleak you will want to pull out your pistol and take some shots while backpedaling, if I'm not on fire I will cloak once I need to reload. This is usually the best if there is a Pyro running for you.

3) A last ditch effort to gain as many lucky knife/revolver kills as possible when you are surrounded by psycho enemies hungry for your blood. Run for the nearest back!

Remember about keeping away from the main path when escaping, jump on objects etc where people won't run into you.

Upon completion of a stab, I usually return to a midway point to return and finish off anyone I may have missed. Try retreating towards their base a short way and uncloaking there. Don't do this if you think they are now too alert, instead leave and find someone else.

I've decided to organise this section more specifically depending on distance and numbers. For purposes of reference, a player moving to Spycheck you counts as being detected. Hopefully you should be able to tell if someone nearing you is alert or not, but if you are unsure assume the worst.

Distant Players

A lone player who is moving to check/engage you is a fairly minimal risk, because you always have the opportunity to run quite easily. I would advise you to leave while you still have your cover and use that advantage to quickly hit another less alert person. You can fight him from a distance easily, too, but don't do it against Scouts and Soldiers.

Many players, knowing you can escape easily, won't bother, but watch out for Snipers. The advice here is for closer threats.

One Player

Usually when you are seen you need to cloak. Fast. If you can't cloak, try to lead them into a sentry or your own forces.

If you are in an area that is closed and easy to Spycheck, then you will have to fight them unless you believe you have the distance to make it away in time. Open areas allow you to cloak and be hard to find, but remember he's on his own, you can always start shooting them. If someone comes or there are nice targets elsewhere then just give it up and take the better options. Alert players are less time-effective.

After turning a corner you can quickly double back and stab as they run past you. Hopefully their reactions won't be quick enough and you can land a back-stab before they turn to attack you.

The next thing you can do is lead them up some stairs and attempt a stair stab. Beware, this is a very hard manoeuvre. Normally you will use your pistol to fight them off.

There are hundreds of small shortcuts or alternate routes a Spy can use when escaping. Learn as many as you can, some are obvious, like jumping over corners, around the opposite sides of posts or up onto ledges usually reached by stairway. The indirect route is best if you are being chased.

When you are being chased and come across a blind corner, you can run around a the corner, cloak, then switch sides to give an Illusion. You can then Stalk them or make your escape back the way you were chased. This is great for corridors as they rarely suspect that you have simply stopped and dodged them. If you like to stalk them while they are chasing your phantom, this can be a good tactic, but as they are now RED zoned. You are better off leaving and targeting someone else while they waste their time. This can be used against higher numbers, but it becomes very risky.

General Tactics

The tactics here can be used for any situation, involving individuals or crowds.

Your greatest strength is obstacles such as corners, height and stairs. Use them.

If you stealth behind an object, they may not realise, and instead follow a teammate or become confused.
If you are in an open area, run and stealth behind an object, quickly leaving as soon as you are cloaked. If an enemy goes to chase your ghost, you may want Stalk them. If you attempt to do this, remember what you have learnt. People that don't see you cloak will have difficulty finding you.

While you are being chased, try to find the class you are disguised as and cloak while out of sight. Hopefully they will instead chase their teammate.

Often times you will be observed cloaking. People guess very easily where you will go by imagining you continuing in the same general direction, usually towards the obvious escape route, and quickly find you. Switch directions, giving them the illusion of heading in the wrong direction.

If you are taking damage, causing your outline to flicker, wait until a break in damage, quickly change direction. Your change in direction will be unpredictable. Obstacles are your best friend.

If you have managed to leave sight and re-disguise, call out "SPY!" using the voice menu while pretending to Spycheck. What kind of Spy rats himself out?

You actually move fractionally slower when moving backwards. This shouldn't effect you much, because seeing what your pursuer is doing is a MASSIVELY greater advantage, but it is useful to know.

The last thing to always remember when playing skilled teams is to think: "What would I do if I was a Spy in this situation?" and then don't do it, as that's exactly what they are thinking.

Class Specifics

These are for if you can't cloak at the time and you are trying to get away.

Always check their health. If they are on low health you are almost always better off to try and gun them down.

Your choices when you are being chased can vary depending on the class after you. The following is a quick look at each class and your options:

Scout
Find a team-mate fast. His low health means you have a slight chance at fighting him with your pistol. Unfortunately, a good Scout will dodge you quite easily.

Pyro
The chances are you are burning. You will have to shoot him and hope for the best. If you can try to backpedal for a healthpack. Try to say away from their fire but don't let the danger and visuals distract you into missing.

Soldier
Soldiers are usually very happy to chase a Spy around, because they are strong and you are an easy kill, you need to get out of sight. You are able to use the Soldier's rockets to give you a boost through the air and away from them if you can time a jump just as the rocket hits the ground. They may have too much health to warrant the use of your revolver, but make sure you keep your distance for shooting. These guys will simply shoot the ground at their feet upon walking into a Spy.

Demoman
Demomen often have the most difficulty killing players when you are up close and in their face. Only begin to retreat if they pull out their Grenade Launcher. Forcing him to alternate between the two is even better. Don't go up close to Demoknights. When they find an invisible Spy they will use their launchers and fire at the most commonly taken route. Beware of the large blast radius, surprisingly, the safest area can be close to the Demoman himself.

Heavy
You are best to find a corner and get out of their line of sight. After that you should be fine. Don't bother with your pistol unless you have good cover and they are distant.

Engineer
Sapping things is a good way of distracting Engineers. Using your revolver is a very viable option. Upon discovering a Spy, they will always try to catch you unless they are busy repairing. You can use the tactics in the Engineer section to take advantage of this. ALWAYS keep out of range of their shotgun.

Medic
Stay out of melee range, the last thing you want to do is gift an Ubersaw Medic a free charge. Use your revolver if you have to fight. Strafe hard to avoid those needles. The Blutsauger will mean you have to do a lot of damage fast.

Sniper
Don't close to melee range with them, don't escape to long range in the open. The best you will want to be doing is forcing him to switch back and forth.

Spy
An interesting class to be chased by, as this is a full on battle of accuracy and wits. Good luck.

Despite being a class that thrives on his own, the Spy offers a huge tactical advantage. Keep your team informed. I would recommend getting a cheap mic if you don't have one for TF2 as it is such a strongly team based game. Warn your teammates of impending sentry nests. Inform when you are about to sap ahead of a rush. Ask your team to wait for your go.

Stay aware of the next cap point your team needs.

If a point is nearly capped, you might want to go there and remove your disguise. You may be able to cap it before the enemy has a chance to react. Alternatively you can be waiting on a cap point for it to become available.

Use your DR to take the first stickies laid at the start of the round, creating an opening for your team without harm to you. For best use, disguise as your own team. You may either return to your base and resupply or continue on. Remember to swap your disguise back to the enemy if you have disguised as your own team.

Remember: the Spy requires a lot of practice and experience and he's not easy to master. This guide will give a great base of skills and techniques, but the real skill comes from constantly practicing. Everyone makes mistakes. Making a mistake does not make you a bad Spy, not analyzing where you went wrong or having no idea what you should have done makes you a bad Spy. The key is to learn from your mistake. Sometimes the line between a good Spy and a great Spy can be hard to find. By practicing and successfully employing these tactics, you can easily outsmart and outmatch any other Spy or player on the battlefield.