First, play control, but don't sit in a flag, sit outside it, behind it, In front of it, and catch people unawares... Camp the heck outta a few matches. Also, like another poster says, use the buddy system, you're MUCH less likely to die if you're double teaming the opponent. I usually go positive, but the thorn mission (with void damage) took me 2 weeks! You'll get it, have some faith!