It depends on where you live/hunt and how cold you expect it to get, wind, etc.
Hunting deer in northern MN and Elk in Wyoming, I find the combination of these clothes to keep me warm 98% of the time. If I use this and still start getting cold, I start walking for a awhile to get the circulation going.
Cap (since 30+% of you heat loss in through you head) I wear a heavy wool outer and thick fleece line cap with fold out ear flaps by "Crown Cap" from Canada. Cabela's has something similar, though I never wore one of there's that's made in USA.
1-2 med-polar weight polypropelene long underwear bottoms by Duofold. (no cotton)
1 polar weight polypropelene long underwear top by Duofold.
1 Polartec fleece sheat shirt top (these are very warm) maybe too warm for all but sub-zero weather. If it's above that I'd weara medium weight wool shirt.
A windproof Gore-Tex insulated hunting jacket over that.
Pants - heavy wool hunting pants. Wool keeps you warmer, even if you get them wet, though never try to get wet, if you can avoid and get dry as soon as possible, if you ever say fall into water.
Socks - 1 pair onlyof Angora goat hair socks from Ada Austin farm Harmony MN. These are the warmest most comfortable socks I ever owned. They cost, but they last and she says mushers on the Iditorod race have worn them. These socks move the sweat away naturally and won't chafe like wool on your skin. Otherwise wear a light polypropolene sock under a medium weight wool.
Boots - Gore-Tex or other waterproof boot with 600-1000 grams of thinsulate for more walking hunt. Felt lined good waterproof pak boot, if you're mostly on a stand will be fine.
Mitts - grommet wool gloves that have the fold over flap to cover your fingers completely and thinsulate lined. I find these best to keep your fingers warm when you waiting or walking and can quickly flip the flap up/back to have finger tips only exposed for a shot or when you need to use your fingers.
Bring firestarter (e.g. lighter, waterproof matches, flint striker and/or strike anywhere matches in a sealing container. If you'd for some reason get stuck out in the field/woods you need that, with your other equipment to survive.) I always think of what I'd need, if I had to spend a day/night in the coldest of weather, snow and wind in winter in Minnesota in planning. That's why I think about the details....
