when ever you get to cover always pick your next bunker. Never get into a spot that you don't have an imediate escape from. If someone is shooting at you and you are afraid of being pinned down, pop out and squeeze off a 5-10 round full auto burst. pop back in and count to 2. Then run to your next spot. by the time you get there they should be thinking about taking another shot at you. Only, wait, where did you go? Oh shit they are out.
Paying also sufficent attention to third personell.