I don't live where we need to store our cars in the winter but I did read an article about storing your car when it's not in use for a long time. One thing that stands out in my memory besides what's already been said was to put some auto wax on all of your gaskets and such that line your doors, trunk, windows, etc. this keeps them from sticking up or tearing when you finally pop open a door or roll a window down in spring when your ready to start driving it again.

I've seen special additives for your oil and gas that your supposed to use when storing a car or boat. A lot of people down here use it for their boats when they're being stored. I don't have a boat and never have stored my car so I can't remember what it's called but I'm sure you could find in an auto parts store.