1) Heat Holder socks
Nothing keeps my feet warm. Seriously, nothing. I don't care how many grams of thinsulate you cram into a boot, it's not enough. Heat Holder socks, however, stave off the inevitable numb toes longer than anything else I've tried. They have extra-long looped, super fuzzy pile inside, and you can feel your feet get warmer the minute you put them on. They have a TOG (thermal overall grade; it's a British standard of a textile's thermal properties) of 2.34 compared to the average thermal sock's .89.