1 - support your maxes you will get more xp supporting him then you will trying to kill steal
2 - if you pull a sundie MAKE SURE YOU HAVE AMMO OR REPAIR FITTED passive xp/certs is great but also helps your empire.
3 - when in a zerg watch out for the 60000000000000 vehicles they will run you over
4 - never think your safe unless your in a spawn tube
5 - always thank your support classes its a shitty job so make them feel appreciated
6 - always clear the corners when entering a room - sounds simple but ive got alot of kills when troops just barrel through a room and dont realise they have been shot in the back by me ( or my engie turret - yes people are that blind to what they are running past)