The first thing you should do is throw away all your heavy socks. Why? Because heavy socks make your boots tight which causes your feet to get cold. So the real key to keeping your feet warm is wearing boots that fit properly. To do this put on a pair of normal hunting socks. The best socks I have ever worn are First Lite Mountain Compression socks. Trace the outline of your foot on a piece of paper. Hold the pencil parallel to the sides of your feet and don’t angle it towards the bottom of your foot. Compare the measurements to these charts. http://www.shoesrx.com/menssizes-1.aspx
Pay close attention to the width. For years I wore 10 regular width but after taking these measurements I found out a 9 EE was what I should be wearing. Let me tell you I was amazed at how good my feet felt wearing shoes that were actually the right size. After this it’s just a matter of buying boots with the proper amount of insulation to match what you’re doing. A new gadget I discovered this past year are the Thermacell heated insoles. I highly recommend these. They don’t necessarily warm your feet but they will keep them from getting cold. I have uninsulated, 600, 1200, and 2000 gram boots that covers from -40 to 90 degrees. If I had to pick an all around boot it would be 600 grams with the Thermacell heated insoles which can be removed for warmer weather. Some people have cold feet and others never get cold but the key is boots that fit.