Here's some good advice that I haven't seen rehashed yet this season.

Keep still. It makes for a sore stiff hunter, but it's really important.
Motion can be seen a long way off; a lot further than you can hear footsteps. I think many hunters get busted because they were seen before they even know there was a deer nearby. The deer goes the other way and the hunter gets convinced there are no deer in the woods.

Make sure you cover your face and wear dark or camo gloves, since these two parts of your body do the majority of the moving.

One very useful technique is to scan with your eyes. It allows you to be aware of your surroundings looking for deer, but not be noticed. Move your head in one direction, and keep it there while you scan your whole field of vision without moving your head. Then move your head to another angle and scan again. You should be able to scan about 90 degrees at a time, and with 3 head turns, you can see everything for 270 degrees without moving any other parts of your body.
This provides much less noticable motion than simply turning your head every few seconds. I've watched new hunters from my stand turning their heads often and almost never seeming to be still.