If it is necessary to drive, make sure that your tires are in good shape, and that your horn, brakes, lights, and all the essential safety equipment is working. Keep your car garaged, if possible. If not, and you have an engine block heater, use it in severely cold weather.
[Note that cold weather can be hard on batteries, so check them; use higher octane gasoline or gasoline additives to prevent gas line freeze ups].