One piece of advise I can give that seems to work out great for me is two fold. First, always, if possible, fire from the prone position. Secondly, get used to switching between single and burst fire. When I enter a narrow alley, small room, or otherwise enclosed area I switch on burst fire. If i'm anywhere else than that, like running down a street, i use single fire. Also, keep in mind that even only shooting single fire, you have to pause shortly between shots. If you fire too rapidly in single fire, you lose accuracy exponentially. If you play as a kit with a short range weapon like the shotgun, use your pistol in any situation other than close quarters combat. It takes some practice but the pistol can be just as useful as the M16, per say. The only other advice i can offer, other than practice, is be as aware of your surroundings as you can. Know where your teamates are, know where coveted sniping spots are, and spot anything you see on the map.