Crouch the entire time to make your blip disappear. If the blips are off or set on "Far", your enemy will not see you until you shoot them (if they survive). If the blips are on "All" or "Near", you can set up ambushes in places with stairwells, such as the apartment complexes. Run up and crouch at the top of the stairs while looking down just enough for you to clip them as soon as they start running up. The blip on the radar shows you are above them, but that is all Ass far as they know, you could be on the roof. They'll be taking shots to the face on the first stairwell because the blip above your head is gone due to your crouching.