My toes are my only real problem. What I do is to put a plastic grocery bag over the toe, then layer duct tape on it until it's a toe cap, then cut that back so it ends halfway down the shoe, cut a cutout for the cleat, then put a couple strips of duct tape towards the back to secure it.

This makes a huge difference in how warm my feet are (or more accurately, now not frostbit they are)

I suppose I should actually buy some neoprene toe caps, but the duct tape chic is too good to pass up.