Under Armor Coldgear leggings, mock turtle neck, and their hoodie, which is honestly fantastic. It seems thin, but really does a great job, just turned my buddy into a believer.
Microfleece wader pants over the bottoms, then my bibs. Reg. socks with a warm wool/synthetic oversock and heavy pac boots. Over the UA top goes a different brands cold weather top, then I go to layering regular turtle necks and shirts. Then my duck hunting jacket goes on. On my head, that UA hoodie along with a beanie, if it is really windy or if I want a bit more camo to help hide my mug I'll put my fleece neck gaitor on as well.
I think one of the biggest things to remember is; Moisture will kill you, even with all those layers, if you are wet you are vulnerable. So paying the money to get these great moisture wicking underlayers is well worth it, this is why I love my UA.