-Always keep an eye on your clip, total ammunition (or battery charge), shield level and health. There is nothing worse than bursting into a room full of enemies with low health and shields, and an AR with seven bullets left in its clip.

-Reload and let your shields recharge at every quiet opportunity, especially before you go running into another fight.

-Don't hang back from a fight just because your health is low. If you are careful, you can make do with your shield. Your shield is your number one defense against enemy fire. Always make sure your shield is as full as possible.

-Try not to let enemy fire dig into your health. Unlike shields, your health won't recharge.

-Pay attention to your Direction of Fire indicators (the red arrows that flash on the sides of your screen when hit) and Motion Tracker.

-Don't use powerups needlessly. Don't pick up a Medkit unless your health is actually low, and don't waste your Overshields needlessly. If you pick up Active Camo, it will run out quickly, so put it to good use!

-Be careful with grenades. Many enemies carry grenades, and any nearby explosion can set them all off, potentially killing you. Ideally, you should keep a safe distance away from any enemies you kill with grenades.

-Try and be mindful of which kind of grenade is best for a certain situation. For instance, if you're trying to flip a pilot out of his Ghost, throw Frag Grenades in his path; whereas if you're trying to destroy the vehicle, try to tag the vehicle with Plasma Grenades. Try and use combinations of both.

-Learn the AI patterns of your various enemies. For instance, Elites always charge madly when their shields are down and they're on low health (which is when they stop, lean forward somewhat, wave their arms in fury, and roar before charging), and Grunts will always retreat when an Elite is killed (which is when Grunts turn around, wave their arms in the air, and shout phrases like "Leader dead - run away!", etc). Each character has different AI characteristics and patterns.

-Learn the strengths and weaknesses for each weapon, and get a feel for them. It's all well and good to read their characteristics in a guide, but that means nothing until you go out and try them out yourself!

-Don't get overly attached to your current weapons; if you're about to face a team of Elites and you're armed with a Pistol and AR, and you've just killed a Grunt, you would be better off swapping your AR for his Plasma Pistol. Remember, you can always come back for the weapons you've dropped.

-In combat, don't forget to use cover, elevation, and other such factors to your advantage.

-Don't forget melee attacks in close quater situations. Melees are a good way to keep fighting if you've exhausted your clip.