Okay some of you may know what a dropshot is, or have heard of it. If you don't know, all you do is when you are in a tight spot you go prone as soon as possible and spray bullets. It give the enemy almost no time to react.
Some tips are using the "Tactical" button layout. Go to options and change your button layout to Tactical. This lets you press down the right analog stick and go prone faster so your enemy will never see you coming.
I personally use Tactical Flipped, because i use the triggers to shoot.