Planetside 2



Shoot them in the head. Also, wear nanofiber armor, and make sure your utility item is a med kit (unless you're an engineer, in which case the ammo pack is the best XP value).
 
In super close quarters, try jumping while spraying from the hip. Depending on your weapon and attachments, you can pretty much hold down the trigger and just compensate for midrange. Long distance you definitely want to fire in small bursts. The medkit certs seem almost too good...I can carry around 3 at the moment and just eat them like candy. Keeps you in the fight for so long.