Socks are the key to warm dry feet. I can hunt in tennis shoes if I have the right socks on. If you are trying to survive the cold, you can't always avoid sweating. Always remember that cotton kills in the cold. Why? because it holds your sweat close to you. You need a base layer/sock that pulls the sweat away from you. The second layer should also not trap the sweat either. Rubber boots doesn't allow that moisture to leave so it has to stay in your boot, hopefully as far awy from your skin as possible. Boots with moisture gathering insoles are great as long as you dry them out every time.
The other thing that has been mentioned and is good advise is the colder the weather, the bigger the boot size. Many people put on too many socks for there boot size, cut off circulation and end up with colder feet than if they wore just 1 pair of socks. Boots that fit too tight are not as warm.
I've got some light weight Xscent socks that I like, and my favorite socks are the Cabela's Igenious socks. They have that scent control built in, make a light, medium and heavy weight that are all the most comfortable socks I've ever had. My extreme boot is A Sorel. Rubber at the bottom, nylon at top, felt liners, and rated to -100. 1 Pair each of the Cabelas light medium and heavy ingenious socks and I can get as sweaty as I need to be and still be able to stop. sit down for as long as I need to. My feet could be soaked and half hour later be bone dry and still warm. Once the insole and liners are soaked, then it's time to dry them out or freeze. My fair weather hunting boots are Rockies, I have both 1200 and 400 gram boots. I've done many of scent drags and use doe gel on my boots a lot. They are not full rubber boots and the deer follow my scent trails just the same. I take extra scent precautions though, odor eators, (the original cabon scent control) baking soda, wash liners and spray boots often. Right now every one of my boots has an onion inside. lol
I've seen the rubber boots being recomended here and think I might have enough room in my truck for another pair but I need a good pair of warm weather rubber boots. Something light and quiet like a tennis shoe yet rubber and at least a little over the ankle for when 400 grams is too warm?