Make sure you have wiggle room (not too tight), and wiggle/move 'em around! Smartwools, or other high quality socks. If on a stand, you may want to put a piece of carpet, etc down under your feet (cold air is constantly pulling warmth away if not...you can tell b/c you'll be warmer if you're on the ground). Heaters for the toes (the charcoal ones you open that heat up and last from 8-12 hours).