Pretty obvious tip here, but I know that I, for one, tend to miss the obvious stuff. You can get a number of hunts out of those heat packs if you put them in a ziploc sandwich bag when you don't need them and at the end of the hunt. Oxygen is needed, and they don't get much if you're not fidgeting or moving. The first time I used them (negative temps, incidentally) I nearly had a stroke when I moved my stand.
When it's really windy, I carry in a light nylon camo kiddie sleeping bag. It actually says "GI Joe" on it, for which I've taken considerable and well-deserved grief. I've been meaning to have a seamstress add some suspenders to it so I can stand up and shoot without it falling down.
In terms of shooting a bow, I've found I can wear a lighter upper if I take care of my lower 2/3rds. A mid-weight anorak/pullover, neck protection, and a heavy hat do it for me.