Check your battery and charging system. Terminals should be free of corrosion. If the battery is more than three years old, have it load tested or replace it. Since cars utilize so many electronics, a good battery is crucial. Old batteries can lose as much as half their power when accessories are used during cold weather.
Good tires are essential and be sure to check the pressure.
For each 10-degree drop in temperature, tire pressure decreases one pound. Adequate tread depth is needed for traction in snow and rain. To measure the depth, stick a penny into the groove with Lincoln's head first. If you can see all of his head, the tires need to be replaced. All-weather tires provide decent grip in light snow, but for optimum traction in northern regions, consider mud and snow tires or special winter tires for all four wheels, such as the Bridgestone Blizzak.