These tips are intended for players looking to get the most out of Mass Effect 2, play it on harder difficulties, and get the best ending possible. We've got tips for combat, setting up your character as well as your squad, and for getting the most out of the dialogue. There are some very minor spoilers for a few bits of the game in here.
Insanity Difficulty
If you're looking to try the game on its toughest difficulty, you're going to need every advantage you can get - especially if you don't want to spend an hour dying repeatedly on each little gunfight. If you've got some solid aim with the 360 controller or a mouse, then play as a Soldier or Infiltrator and use basic abilities like Adrenaline Rush and some kind of ammo power to headshot your way to victory. If you're more the armchair tactician, then a power-oriented class might be better, but you'll need to stack your squad properly, use the tactics menu often to place them behind cover, and keep using their abilities as soon as they refresh.
One big change you'll find with the higher difficulties is that pretty much everyone has armor or shields on top of their health, and often both, so you'll need to be using abilities that properly target these defenses if you don't want fights to take all day. And on Insanity, you can go from full health to dead in a second if you are out of cover at precisely the wrong time, so make sure you're popping back behind cover whenever a rocket or Warp is coming at you.
You're going to need a lot of money, too, so Insanity is best attempted on a second playthrough and only after you unlock the extra cash, minerals, and XP bonus from beating the game the first time. You don't necessarily need to import your previous character, and you can definitely make a new Shepard and survive. But at the very least, importing an ME1 character for the other initial credit bonus is very handy. It does help if you have some weapon and armor upgrades from the various pre-order bonus and Collector's edition DLC. Play around with them to see which work best for you.
Zaeed
Zaeed might seem like a throwaway DLC character at first, but he's actually pretty interesting. He is fully integrated into the game and cusses a lot, but instead of throwing a screaming tantrum like Jack does, he's got a scowling British scumbag style that I think you'll warm up to. If you're looking to add a little Guy Ritchie to your Mass Effect 2 experience, he's the way to go. Don't forget to check in with him in Normandy's cargo hold for some amusing stories, and his Inferno Grenade is a hell of a lot of fun to use, too!
Cooldowns
One thing you'll eventually notice is that your squad's AI isn't completely braindead most of the time, but they could sure do a hell of a lot better. For one, they often leave key abilities sitting on cooldown, so what you should do is pick the best general use power for each character, max that out, and then map it to a quick key or button to press manually. You'll get a hell of a lot more use out of it that way. The fun part is that even if your squadmates are around the corner from an enemy, using their abilities manually is based on your line of sight, not theirs. The end result is that you can have characters hang back and throw powers technically around corners when you activate their abilities yourself. You don't even have to pop out from cover to use them!
Ammo Powers
The ammo powers can be a little confusing at first; in all, there are six of them, and they all are a little different. Warp Ammo comes from Jack's unlocked power (and can be picked up by Shepard with the Advanced Training research upgrade) and will do a smaller amount of additional damage than some, but it damages shields, armor, and health equally. Cryo Ammo freezes targets once they're down to just their health, Disruptor hits shields and shorts out synthetics, and Incendiary damages armor, leaves lingering damage to health, and leaves people flailing around. Finally, Shredder Ammo takes down just health very quickly, and Armor-Piercing deals extra damage to armor and health.
In most situations, you're probably better off streamlining this by picking one squad version of an ammo power and sticking to it, switching only if you need it for a particular mission - Squad Warp Ammo is good all around, and maybe you can swap to Squad Disruptor Ammo if you're going up against the Geth or Incendiary or Armor-Piercing for armored opponents. If your Shepard is a Soldier, Infiltrator, or Vanguard, that's the perfect character to put some squad-based ammo on since Shepard's always in the party. If you are one of the other classes, you can still do it by adding an ammo power with Advanced Training later in the game, or you can turn it on with a different character that you find yourself using often.
When to use abilities
It's vital to understand when certain powers are most effective. You'll find that many of them are almost useless until the enemy's Health bar is showing - Throw, Pull, Dominate, AI Hacking, and Slam are good examples of this. Samara's Reave and any fire-starting ability work best against armor and not so well with health or shields. An Adept can combo Singularity then Warp to do damage to just about anyone. It's important to read up, understand what works best against opponents in the right situations. And if all of that fails, you can always try shooting your enemies in the head!
The game never actually lets you look at every power in a big list at once, so it may be a little difficult to put together combos without starting to write down which character's abilities do best in which situations, but this list at the Mass Effect Wiki will help.
Curving it
If you've got abilities that are thrown like projectiles, you'll need to curve them for maximum efficiency to hit enemies hiding behind cover. Some abilities, like Reave, absolutely require a clean line of sight to the center of mass, so they can't be curved. Anything that has a projectile will hit enemies behind cover if you can send it at the right angle. All you have to do is aim away from the target in the proper direction while keeping the enemy you want to hit still highlighted, and your projectile will fire in that direction and then curve in towards the target. This does mean that even as an Adept you might need some practice aiming, but the nice part is that you can do this bit of aiming from behind cover and before you fire the power.
