The biggest cause of cold feet is trying to pack too much sock into a boot. It stands to logic that the more or bulkier the socks that you put on, the warmer your feet will be. If your boots can't handle it, nothing can be further from the truth.
As others have said, you must have a boot capable of handling a "heavy sock load". Purchase a boot that fits you needs and make sure you bring your cold weather socks when you try them on. You foot should fit nicely in there even with enough sock to choke the michalin man.
My personal preferance for foot wear is the 18" LL Bean Guide Boot. There is no insulation in this boot. I have two sizes in this boot. 11.5 and 12. For warm to mid range cold (down to 15*) I wear a polypro sock(very light) I then wear a tighly knit wool poly blend and add the smaller boot. For the cold stuff below 15* or so I add a 100% rag wool sock over the other two socks and step up to the old size 12.
I perfer a noninsulated boot. If you get one of those insulated jobs wet at a stream crossing you sunk. You've got a giant icy sponge on your foot and you can't do much about it. Even after a night of drying over the wood stove, that suckers gonna be wet. With an unisulated boot, all ya gotta do is swab it out with a t-shirt, change your socks and you rolling... Much more efficient and much safer.
This system got me through more upstate NY winters than I care to think about. We routinely hunted in sub 0 temps up there. When your deer camp looks like this, you learn a thing or two about how to keep warm... This was taken just as the rut was peaking....