Also, as with any strenuous outdoor activity, two critical things: 1) Keep your core warm. Long underwear, especially. The more your core stays warm, the less your body will pull blood flow from the extremities and the less your hands will get cold. 2) Keep your skin dry. The more you sweat, the more the cold air will chill you. Wear a runner's base layer that wicks the moisture away from your skin, and then layer on top with wool for both warmth and fire/spark protection. Cotton holds moisture and is NOT your friend in the cold.