The simplest thing you can do to combat the cold weather is to keep a few essential supplies and tools with you as you drive. You'll obviously want a spare tire and the tools to change out a flat, but it's a good idea to keep some extra material in the trunk as well. Bottles of engine oil, washer fluid and coolant all come in handy, and we'll touch on those in greater detail later on. An ice scraper is a necessity, since you and your car won't be going anywhere with frozen snow blocking your view.
Flashlights and flares are helpful if you're stuck on the road late at night when visibility levels are low. Even if you're wearing a coat, an extra pair of gloves, boots or even a blanket can keep you warm and dry if your heating unit isn't working properly.