Buy the Engineer class and spam the flechette shotgun and the health and ammo drops at every battle.

Lower unit diversity is key to victory, as purchases such as Demolitionists or Snipers would simply be a waste of credits and manpower. It's better to have an army of well equipped regular troopers with the occasional braindead Engineer bot that only uses a fusion cutter than a horde of largely useless Demolitionist and Sniper AI which will mostly use standard blaster pistols. (There is a notable exception to this, being the Droideka on the CIS side, for reasons discussed in Section 3.)

The same applies for Space units, as the Marine is generally useless due to the bots' ineptitude at killing enemies whilst onboard their ship. You may be tempted to purchase this unit to play it yourself, but the Marine's explosive weapons take much longer to damage the enemy ship's systems than the Pilot's Time Bomb. Thus, the free Pilot is the best option, considering that the Marine doesn't have the vehicle health regeneration bonus.

Using credits from victories, repeatedly buy the Garrison bonus for 2 slots and Sabotage in the remaining slot in the event of a space battle. In the mid to late game, when you are swimming in credits, switch to buying the Enhanced Blaster bonus instead of Garrison.

The Garrison bonus gives your team extra reinforcements when they start to run low, which can help if your team is struggling on a particular planet. It's also extremely cheap at just 200 credits, so you should be able to afford purchasing it every turn. Even if you think you won't need it, an insurance policy never hurts.

Later in the game, use the Enhanced Blaster bonus on every land battle as it not only beefs up your flechette shotgun, which is already a slaughter machine, but it also gives the brainless AI on your team a higher chance of winning the gunfights they throw themselves into.

Enemy bonuses don't matter as the AI usually only uses largely ineffective bonuses like Bacta Tanks or Garrison. Although it may seem like Garrison would give the enemy team a chance to compete, as long as you are sweeping through the bots with your enhanced flechette shotgun, by the time the Garrison bonus takes effect, you will still have a massive advantage.

Should the enemy fleet engage you in a Space Battle, just use Sabotage to cripple their chances of winning the battle and go make a sandwich or something while the AI on your team mercilessly annihilate them.

The AI are full of weird quirks that make them easier to eliminate.

The most infamous quirk belongs to the Rebels. Upon killing a stormtrooper, the Rebel bots will perform a strange ritual where they gather around the corpse and violently blast it with their blaster pistols, even when under fire from an enemy. In fact, they will look straight at their attackers while shooting the corpse, perhaps signifying that although the bot knows there is impending danger, it cannot go on without fulfilling its duty of shooting the everloving crap out of the corpse. This will allow you extra time to close the gap with your flechette shotgun.

On Naboo, the AI will occasionally get stuck in a corner of the map. This can work for or against you, as sometimes the AI on your team will be trapped in this corner as well.

The AI have an obsession with turrets. Should your enemy invest into Engineers (a worryingly intelligent decision), they will mindlessly throw themselves into danger, Fusion Cutter in hand, to repair and man a turret. Should they manage to survive the repair, they will enter the turret and refuse to leave. This makes them easy targets for your Detpacks. The same applies to your team's Engineers, but you should be able to pick up the slack.

The AI pilots have a bad tendency of just standing around in their ship doing absolutely nothing. Although this makes boarding the enemy ship feel like fighting an army, it also means that your AI fighters will face less opposition on the battlefield. Combined with the Sabotage bonus, this will give your team the distinct advantage.

When the AI play as a class which has a Recon Droid, they're highly likely to throw the Recon Droid and use it until it is destroyed. So, if you see a Recon Droid flying around, you can be sure that a defenseless enemy is nearby. Hunt them down and eliminate them before destroying the Recon Droid. In addition, avoid purchasing units which have a Recon Droid (MagnaGuard, Clone Commander, Wookiee Warrior, Imperial Officer), or your teammates will do this as well.

Certain factions offer certain advantages you can use to your disposal.

If you are playing as the CIS, the area outside the airlock on Polis Massa will not affect you, as you are mechanical. Use this to your advantage by taking cover from enemy fire by exiting the airlock or by navigating to command posts through the outside of the map.

Also as the CIS, you have access to the Droideka, arguably the best unit in the game. This is the only other unit I'd advise unlocking other than the Engineer, as it has massive damage potential when deployed en masse.

Certain factions have help from native species on certain maps. The Republic/Rebels have help from Wookie allies on Kashyyyk, the CIS have help from the native Geonosians on Geonosis, and the Rebels receive help from the Ewoks on Endor. The difference these factions make is minimal if they oppose you, but they might manage to off a few of your foes should they be on your side.

Congratulations!

You've learned how to turn Galactic Conquest from a game of strategy to a matter of when you will inevitably win!

Although, I'm not sure if that's such a good thing.