Layers, wool and fleece. Keep your hand, feet, head & neck warm(take extra of each). Hot hands are great for boots, mits or even in your hat. Polyproplene is the cold climate hunters best friend, I wear 1-piece when it is extremely cold and 2-piece all other times. I also use polyproplene sock liners under a good quality wool sock. Boots thinsulate and gortex. Avoid caffine at all costs, while coffee might make you feel warm it also makes you void and this causes heat loss(think of your void as antifreeze). I drink only water and eat foods like PBJ, granola, oatmeal, etc. Don' t heat your truck up to hot, just enough to keep the windsheild clear and don' t rush to your stand. Wear as light a layer in as comfortable for walking. If your sitting in a blind or in a stand take a sleeping bag to zip your bottom half into. If you feel stiff or sore, stand up, stretch and create some blood flow. I like to wiggle my toes and finger tips when I start to feel chilled.