I think you got some good advise from everyone, and I strongly agree with Ratllesnake1, just like some of us say "we have a sixth sense" and a deer's nose is 1000x times better than ours, I belive a deer's sixth sense is 1000x better then ours. Unless there is alot of cover and/or distance (30yrds+) between a deer and I, I will lower my head (so my hat brim hides my eyes) and peek, not stare at him every once in awhile. Whenever most of us stare at a person and they all of the sudden turn and look right at you, most of us turn our heads away. Well you cant make any sudden movements, even with your eyes when a deer does this to you, so you are forced to keep staring at it, well then your brain keeps telling you "your gonna get busted" and then the "adrenlin shakes" start coming on, more so when a deer is 20 yards or closer and that can expose you much easier or worse cause a rushed shot. This may only happen to me? If I spot a deer coming in I will camo and postion myself as best as possible, check everything (loose clothing, arrow on rest, pull face mask up, hat down) to avoid mistakes, and use my camo to the fullest.
Another thing is ... dont stay in a stand location for to many days. Deer know everything in their area and to much traveling to the same spot will start to keep deer on edge, before they avoid the area all togther.