Whether you go into the woods with a gun or a camera, there are are two basic rules which cover the clandestine observation of wildlife: stand still and don’t smell.
Not smelling is the easier of the two. The first thing is not to leave the house smelling like a cocktail of herbs, spices, and tropical fruit. Use unscented soaps, shampoos, and antiperspirant-deodorants. The second is to wash your hunting clothes in an odour removing, UV brightener free, detergent. The third is to wear a scent eliminating base layer (tech speak for underwear). The fourth is to spray your outer layer with scent eliminator, paying particular attention to usual places where the body tends to be warmer. Spray scent eliminators come with or with out a covering scent. I use one without a covering scent on my clothing and one with a scent on my boots and pack.
Of course, all of the above merely reduces and obscures the evidence of your presence carried on the zephyr. It will not make you completely odourless; you still have to pay attention to wind direction. However, on a still day or in a light breeze, it will make the difference between a deer stopping to nose the air and an erect white tail rapidly getting smaller as its owner bounds off into the distance.