Full tank of gas.... Condensation will build up in your empty tank while going through temperarature changes, so its best to have the tank full. Remove the battery: You car will be dead by next spring from it sitting there, so bring it inside and hook it up to your battery charger. If you bring it to a garage for the winter, they require that your battery be removed for fire safety. I also stick some old rags in the tailpipes. Ive heard of animals finding their way in there. I have also had some mice living in my dirtbike, and eating away my whole foam air filter one season. So cover those pipes! Try to park the car on an asphalt surface, having moisture under a car, teamed up with dirt = rust. Get a breatheable car cover. Breatheable meaning the car cover can let air and moisture escape. Some of those expensive, heavy car covers trap water under there ALL winter long.... imagine what its like to have water marks embedded all winter long. Also.... if the car is outside, try and clean off the snow for this reason (moisture). When you get your car running in the spring, do an oil change as soon as you decide to put it on the road.
Thats all i can think of.