In addition to some "high-tech" tinder I like to have a small (or bigger) candle and birch bark with me.
My experience is if its too cold, even the fine thin pieces of the birch bark don't catch the sparks from ferrocerium immediately. But it's excellent tinder if you have bigger pieces too. Quite water resistant, non toxic and reliable.

One tip: when you need to make a fire but your hands are already cold and fingers numb, light a candle with your match/lighter first and then warm your hands above the flame whenever you need while gathering wood and preparing the fire. You might need to make a depression in the snow for the candle in order for the wind not to put it down.