What George just said!
Also, start paying attention to what exactly the wind is doing in different places you are hunting. Some things I've noticed are these:
1. In hilly terrain, the thermals are usually going down in the morning when it's cool and switch to going up later in the day.
2. Regardless of the wind direction, if it's not too strong, there is usually a "lull" to almost dead calm just around sunset.
3. Wind is like water and swirls and eddies are formed by terrain features. If you are in a block of tall timber and the wind is from the west, when you are on the east side, the wind will swirl from the east back towards the edge. I think there is a bit of a vacuum/venturi created as the faster moving air goes over the tops of the trees and it pulls air into the woods on the downwind side.
4. See #2. It also applies to hills and ridges. If a ridge runs north to south and wind is from the west, it will swirl on the downwind side and depending on wind speed and steadiness, will "puff" from east to west on the down wind side. Think of an ocean wave as being the air going over the top of the hill and the undertow is the reverse swirl. Some days it almost seems like the woods are breathing in and out....
5. If the wind is "puffy" back and forth, try to set up or still hunt at 90 degrees to it. Crosswinds are just as good to hunt as wind in your face, probably better. If the wind reverses, it's still a cross wind and you are "safe".
6. If the terrain isn't super hilly or the hills are not very tall, sometimes you can go up higher in a tree and get above features that cause the swirling and the wind will "straighten out".
7. Try the scent eliminator stuff if you want but don't get your hopes up too much. I think it helps but I really don't believe it works as well as some people would have you believe. Kinda like camo clothing. However, personal confidence is awfully important. Think of it as sort of a "lucky rabbits foot". Maybe it works???....