I have to agree with the right layering: Polypro or silk or wool so you don't get wet underneath and wool on top. Keeps those muscles warm. I wear glove to keep my hands warm. I have to take the right glove off at shot time but I do fine with the glove on my left hand
I also keep drawing the bow unless there are deer around. Then you have to stay still but not long enough to get that tight. I think pulling on the bow also keeps the form good so when you have to make the shot it's not like your first shot.
sam