i would recommend getting a set of good snow tires....with rims or use the ones currently on your car. some places to look for deals on both tires and rims as a set of 4 is tirerack.com or discountire.com, each of these sites i have used in purchasing snow tires for my vehicle and had excellent results.
Another thing to make sure your battery is not corroaded around the terminals, keep these clean. They sell terminal brushes at many auto stores to clean the terminals on the battery. Also, have your battery checked to make sure it can withstand a cold start. If its older then 8 years, I would recommend replacing it with a newer one.
Check your belts for cracking, your brakes, fluids, and your lights.
Its handy to also have blankets, flares, some sort of food, matches and a map. I hope this helps.