Ive seen a lot of people on the forums that need help with the game and general tips when playing. I'l start off.
If someone is behind the cover you are currently covered by, jump over the block and the resulting kick in the face for them will stun them long enough to kill them. One shots have a line sight and when its pointed at you it means get out of the way or your screwed. On wingman try to get as far from your spawn point as possible and dont get near a recognizible landmark.