One of the tricky things with winter riding is safety.
lights are key. Especially here in Minnesota, we are biking in the dark, and, well, there aren't many street lights on the roads I ride either. I tend to ride on the bike trails, non-major/neighborhood roads, and other paths.
Having a bright headlamp is good, but I realize that having an even brighter handlebar light has additional utility.
add reflective patches to your backpack or bag
a bright front light
two rear red blinky lights