Make certain your battery is holding an adequate charge, since batteries are less efficient'and engines more demanding'in cold conditions. Your mechanic can use a meter called a 'load tester' to simulate the effects of cold-weather starting and determine whether the battery is adequately charged.
Be sure your tires are adequate for whatever climate you live in. For most regions, all-season tires with plenty of tread are adequate, but mountainous and northern places often call for snow or studded tires.
Make sure your tire chains are the right size and type for your tires. Mismatched chains can cause tire failure.
Regularly check tire pressure in frigid weather. Tires lose roughly 1 pound per square inch of pressure with each 10-degree temperature decline. Never reduce tire pressure in an effort to increase traction in snow, ice or mud.
Make sure your windshield wipers and defroster are in good repair and that your washer reservoir is filled with antifreeze washer fluid (not all washer fluid has antifreeze capability). Keep snow and ice from accumulating on windshields, windows, rearview mirrors and headlights (see related eHow 'Remove Ice From Your Windshield').
Be sure your radiator contains an adequate mixture of water and antifreeze for utmost protection.
Although it's tempting to neglect a dirty vehicle because it'll probably rain or snow again anyway, road salt, slush, grime and the like are particularly brutal to your car's finish. To minimize rust and paint damage, regular washings and waxes are necessary. Full or self-service car washes make the task much more tolerable in cold weather.
Brake, accelerate and turn slowly. Keep plenty of distance between cars. You never know when you will hit an icy spot.
Pump the brakes slowly and gently if your car lacks antilock brakes. If you start to skid, let up on the gas and the brake, then shift into neutral. If your rear wheels are skidding, turn smoothly in the direction you want to go. If the front wheels are skidding, avoid steering until the car slows enough for the tires to regain traction.