There are some important things this game doesn't outright tell you. For example, I finished the entire game without realising that there is a fast travel system. If you enjoy figuring stuff out on your own, then don't read this guide. If, however, you're afraid of missing out on some cool things, then this guide is for you. No spoilers contained.

At some point, you are asked what your name and date of birth is. If you're like me, you probably wondered what kind of name you are expected to input. Do NOT name yourself "Big Boss" or "Snake" or any other obvious callsign. Give yourself a male realistic full name, like "John Smith". No titles. As for the date of birth (and appearance, for that matter), it's totally up to you. Rest assured, though, you can change whatever choices you made by simply replaying this episode from the Mission List.

Every major outpost that is connected to the road system and has an icon on your iDroid map (except for one, if I remember correctly, which is the enemy's HQ) has a box loading area. You can easily recognise this by its large orange metallic platform. If you have trouble locating it, it might be useful to know that it is always next to a main road (the kind that trucks use to move around) and that it is highlighted by your Night Vision Goggles. On the sign next to this platform, there is a Delivery Point Invoice. Taking it unlocks the respective outpost as a fast travel location. In order to fast travel, you must crouch on the platform in a Cardboard Box and press the corresponding button when the prompt shows up. This won't work if the outpost is suspicious or alerted. Remember that you can also fast travel within the Mother Base, instead of driving from deck to deck or flying. The base's box loading areas are similar, albeit smaller.

When you complete Mission 13, you will unlock a series of Side Ops referring to a Legendary Gunsmith. Do those as soon as possible, because they unlock the ability for you to fully customize your weapons. If any of the Side Ops don't show up on your map, it's because there is already another active Side Op in the same location. Finish that one, leave the area by helicopter, and then the correct Side Op will have appeared. The Side Ops you need to complete are Side Op 107, Side Op 108, and Side Op 109, which are situated in Bwala Ya Masa, Afghanistan Central Base Camp, and Yakho Oboo Supply Outpost respectively.

After finishing Side Op 51, return to the Medical Bay. On the main deck, on the second floor (third for Americans), you'll find an unlocked door with a blue light over it. It's also usually guarded. Go through and there will be a second door that should also be unlocked. If it's not, try going one floor up and turning off the power generator. (I remember turning off the power at some point, but I don't know if it's relevant, and Kamikaze in the comments claims it is. I googled it and some people report that the second door is locked for them, so I'm including this bit of info.) It is advisable that you return to this place every time you finish similar Side Ops.

As soon as you have developed Capture Cages, always bring them with you in your missions and just lay them wherever you feel like. They'll always catch something, and it's always to your benefit/profit. Even if you just put them all at the landing zone right next to each other, they'll still work. Plus, if you're going for 100% completion, It'll also make your life easier, because you won't have to farm/grind this activity after you've done everything else.

If you have problems with the iDroid loading for disproportionate amounts of time, try playing in Offline Mode. Know, however, that when you play in Offline Mode, you will not have access to any of the "yellow" features, like Challenge Task Rewards, Online Dispatch Missions, and FOBs, which is a shame. The loading times have gotten better after the latest patch, though, and the features are worth the inconvenience, in my opinion.

After Mission 21, if you are not playing in Offline Mode, you will unlock your first FOB. This is the online component of the game, where you can invade other players to steal their stuff and other players can invade you and steal your stuff. If you don't enjoy PvP, make sure you never invade anyone else, because the more you invade, the more others will invade you. I have never invaded anyone, and, so far, no one has invaded me. You may play the Event Missions, where you invade NPC-controlled FOBs that will never retaliate. These missions change from time to time and usually offer unique rewards. Regardless of whether you invade others, though, make sure your Security level is high and that your FOB is well-equipped, because it affects your PF Grade. Your PF Grade is an automatic system of virtual "fights" with other players, where the winners get PF Points, which are then used to purchase resources. These leagues are automatic, so you don't really have to do anything, but you may want to use your Anti-Ballistic Missiles or Liquid Carbon Missiles to boost your defense or offense respectively. I never bother.

At some point, you will unlock the ability to sell some of the resources you have gathered. Normally, you shouldn't have to sell anything, so this is only for when you really need money fast. If you're a hoarder like me, you'll probably be afraid of selling anything in case you "may need it later". So, feel free to sell most vehicles, but keep a few of each around because they're needed for the Key Dispatch Missions. If you've finished them and got the Deployment achievement, feel free to sell everything. Don't worry, you can still replay certain Side Ops where you can extract all the armored vehicles you like, and you can find jeeps and trucks everywhere. The gun emplacements are used for FOB missions. If you're not interested in that (or your PF Grade), you may sell those as well. Gun emplacements always respawn after a few days (or a few missions) in the Area of Operations, so you'll never run out of them. You may also sell non-prototype walker gears. (NOTE: This section is no longer entirely accurate, because of updates in the online gameplay mechanics. Most military resources (vehicles, weapons, etc) are now useful for PF contests.)

• Unless you plan on using it for heavy combat, don't bother upgrading the helicopter because it will make deployments extremely expensive.
  
• Make sure you fully upgrade the passive bonuses of the Prosthetic Arm as soon as possible, especially the Medical, since it doubles the amount of plants you gather (credit to Dredd).
  
• The AM D114-9 Handgun can penetrate riot suit helmets.
  
• Anti-materiel rifles are immensely powerful, as they can destroy anything from antennas and guard towers to armored vehicles and helicopters.
  
• At some point, you'll face a certain type of soldier that is a pain in the butt to extract. Don't worry, you'll soon unlock an upgrade that allows you to extract them without problems.

Image by こよりん[koyoriin.tumblr.com].