I can't speak to staying safe on the streets of New Hampshire, but in Buffalo it's mostly a matter of visibility (when running in the dark) and traction.
In terms of visibility, my thinking is that if the astronauts on the International Space Station aren't calling down to ask what the slow-moving bright spot in the Northeast United States is, then I'm not lit up well enough. My typical kit includes two strobes (one clipped to the front of my fuel belt or jacket, the other clipped to the back of my shirt collar), a reflective vest (I have an Amphipod Xinglet), and a small LED flashlight. I also have a reflective Brooks Nightlife hat that I'll typically wear in the morningsand a reflective Brooks Nightlife jacket that I'll wear in the rain or cool -- not cold -- weather. My neighbor commented the other day on how easy I am to spot when I'm out running, so I figure that's a good thing.
As far as traction goes, I don't tend to worry too much about it in the snow. Most snow in my area isn't too slippery; it's more hazardous when it's slushy. When it's icy, though, I rely on my Get-A-Grip Ultras. Others have reported good success with YakTrax, and I've had my eye on the Stabilicers sports. The YakTrax provide traction via a steel spring wrapped around a rubbery framework that fits over the bottom of your shoes. The Stabilicers and Get-A-Grips use small metal cleats.
Still other folks just take short hex-screws and drill them into the bottom of some nearly-ready-to-retire shoes and use those. Positive reports for those as well.
For me, motivation comes from having a marathon scheduled in Cleveland on May 17. Run now or suffer in May, I guess.
Don