I find the best way to stay warm is to add layers after I get where I'm going and going to be sitting. getting dressed befor I get to warm accessing my stand and get cold much faster.
In really cold weather(sub zero) I wear wicking long under wear including a T-shirt, a fishermans knit sweater(high collar), polar fleece vest, and wool bibs. I have a fanny pack, that carries my essentials including chemical hand warmers. To the pack I strap a down jacket and a pair of breathable, wind/waterproof over pants(light weight full length side zipper nylon) and a pair of insulated over boots(if I'm using the same stand I just hang the over boots there and not pack them around).
When I arrive I put on the wind pants and jacket, put a couple hand warmers in the overboots get comfortable and good insulated hat is a must.
This is the down jacket I use.
http://www.llbean.com/llb/shop/64386?feat=506569-GN3&page=reversible-down-jacket