Low and Slow
If your ever trying to sneak up on someone, stay low and move slow. The slower you move, the less other peoples eyes will notice you. Same goes with staying low, the lower to the ground you are, the harder it is to notice you, plus, your also a smaller target. Whether your filling a sniper recon or assault role, if the other team hasn't noticed you, stay low, and move slow. The only true time to go high and fast, is if you have been noticed in the middle of an open field, at that point just RLH. Get to some cover and provide covering fire for the rest of your squad/team.