Heres what I do to keep warm. Mind you that I typically hunt Northern NY from mid November thru mid December. No Cotton first off! In the backpacking world they have a term "cotton kills" and that is so true so just dont wear it. My layers are based upon what we typically wear here at work (U.S. Coast Guard) so we have a great understanding on what it takes to keep warm. Especially in 30 degree water for hours at a time! LOL! We always wear the polypropelene base layer then the polar fleece body suit. A water tight dry suit is the last layer and that isn't very thick at all so If you go with a goretex lined coveralls or bib/parka combo you should be good to go.

layer 1: B.A.N (butt @$$ Naked) NO COTTON NOT EVEN SKIVIES!!! Put a good layer of polypropelene pants and shirt. This is the ultimate wicking material. Under Armor is pretty good but there are cheaper options that will do the same exact thing. You are paying for the name when you use under armor.

Layer 2: Get polar fleece body suit or pants and shirt. This is a secondary wicking material and will keep you warm.

Layer 3: A good set of Insulated winter coveralls or bibs and parka combo. This combo should be well insulated and water/wind proof.

Hats and gloves: Use a good fleece or wool hat that covers the ears and use dual layered gloves that are insulated and water proof. A fleece hood with a bacalava work awesome.

Boots: If you sit all day get a good set of pac boots (2000gram) or if you walk alot get lighter gram boots. Use polypro socks and then fleece or wool socks over them. Make sure you buy boots a 1/2 size up or more to fit with the sock layer. Tight boot= frozen feet!

This is what I have used for years now and I can sit for hours whiole others go back to camp. I hope that this info helps out.

Mack