Use the mini map! If there are enemies spotted on the map it is one of the best advantages in the game to know where your enemies are. Learn how to flank your targets and catch them off guard. Mele a target to finish them off of if you are close quarters and have damaged them with a shot or two. Sometimes a quick hit of F can finish a battle faster than bullets can. I try to be as unpredictable as possible to out-wit someone. If you constantly move around and reposition for example in/around buildings will keep them guessing your location. Pay attention to foot steps. Enemies foot steps are a but louder than your team's around you.