Tricky...
What I do is I move slowly. Im talking about a few inches every now and then so the observer mistakes that as natural (if he is that smart). Its like when you KNOW u made a lot of noise that kinda sounds un natural, i stop, look, and listen for a few minutes and to let the observer pass the area ( or look away). ALways assume someone is watching you.
i aint no Scout/Sniper yet, but I have 'war games' and also stalking deer. Hell, a few days ago I was walking by my treeline and I just had my BDU jacket on with my boonie that had grass on it, and I came across a 4-way and I stopped, and long behold a 6 point buck was at my 11. He started to come my way but I backed out and carried on with what I was doing.
But anyways, once you make a noise that sounds diliberate to the observer, STOP RIGHT AWAY. Then carry on after you asses the AO.