^^^ could'nt have said that any better myself.
Every map has it's central zone that people tend to keep flooding in. (anyone who has ever played the game more than 2 days knows what im talking about.
once you find alternate spots around that central zone but able to peek in and out constantly and move to another spot is when you start seeing how split seconds matter and you will 8/10 times get the kill.
always look at your map for enemy fire. and when theres 1 enemy, theres almost always another very close by.
hope that helps. good luck