In addition to wearing clothing that will insulate even when wet (wool or thinsulate, for example), make sure, absolutely, 100% sure, that you can light a fire or stove anytime you need it. When I hunt, I always carry a homemade "fire kit": half a dozen strike-anywhere matches dipped in wax, a candle, a cigarette lighter, a wad of waxed paper, and several small sticks. I figure I can scrounge up the rest if I have to light a survival fire for warmth and signaling.
EDIT TO DISAGREE (HALFWAY) WITH NEXT ANSWER:
No booze in cold weather! That feeling of warmth is the heat leaving your body, and you will actually get hypothermia much faster.
A good woman (or man), however, could help a lot, I suppose.