Use scent free laundrey det, don't smoke (even if hunting into wind) wear rubber boots with your pants tucked in. When Ronn says look for parts of deer look for the backs of the animals. Most objects in the woods are verticle. Train your eyes to look for the horizontal lines. Focus in on any white objects representing there throat patch, belly and tails. There wagging tails create flashes of white which get them busted almost every time.
A brown animal against a brown background is very difficult to see. Deer are patient and curious when suspicious. In my treestand a few weeks ago I had one stand motionless for 20 minutes waiting for me to move.
You will get sound advise from many users on this site.