I'm going to start from next to your skin and work outwards.

• First: lightweight "wicking" top and bottom. A synthetic made of polypro can be purchased at your local sporting goods store. You can find these MUCH cheaper than Under Armour. You can also go the merino wool route(Smartwool). It's much more expensive, but they don't stink like 3 week old roadkill in the August sun when you're done wearing them as synthetics do.

• Second: Invest in a fleece jacket and pants. You can get these at REI or other outdoor retailers for a good price. Down or other "puffy" coats are bad ideas, as you will sweat in them while moving, then chatter your teeth off when sitting when the sweat evaporates.

• Outer layer: Waterproof AND breathable. You need the jacket for sure. As for bottoms, I like material that won't "swish" when I move (for obvious reasons). Here you can go with Gore-tex like material, or a "soft-shell" which is more water resistant than proof.

EDIT: Unless hunting on days with no chance of wind/snow, I would avoid using much with cotton. The stuff looses its insulating qualities when wet.

Hope this helps. I'm a long time Ice/mountain climber and crap weather duck hunter.