I frostbit my feet badly 30 years ago, and have fought with cold feet ever since. For me, wool socks inside Sorel Arctic packs are the best. The ones rated to -100 (yeah, right!). Unless there's more than a couple of inches of water on the ice, then it's rubber baffins. Disassemble them at night to get them perfectly dry and don't lace them up too tight. Wear water-shedding pants or gaiters outside of the boots for drilling. Also, if I'm fishing out of the truck or permanent shack, I take a dry spare pair. If my feet get cold, even it I don't think that they're wet, I change out. Usually fixes the problem.