When it's cool out I wear a Buff over my chin, and pull it up over my nose and mouth from time to time, on descents and when I'm not breathing too hard. (Once it gets below freezing this doesn't work as well 'cause it gets saturated with moisture that freezes). Once it gets really cold I wear a Buff with a hole cut out of it for my nose and mouth, pulled up over my nose all the time. And blow snot rockets. 
Oh, and cool-weather gloves really need to have those soft fuzzy areas on the tops, large ones. I have a pair that have some sharp seams there and I'm forever cutting my tender nostrils on them
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett