From cold Chicago, CHANGE all fluids. Either empty the tank or fill it and put in fuel stabilizer such as Stabil. The fiberglass tank comes into play here. I have never overwintered a glass tank yet. Mine is empty. Make sure the tires are at or over the recommended pressure. Park it on a piece of plywood with some carpet on top. Remove the battery and bring it inside if you can, other wise keep it fully charged. A breathable cover is good. I use a bed sheet. They breathe pretty well. Thats about all you can do unless you can bring it in the house.
I keep mine and my HD in an unheated garage. The worst is when its really cold and then the temp goes up. It can trigger some mean condensation on the metal surfaces. At that point, I uncover mine and put a fan on it to help dry it out. Dont worry, it will survive.
MikeM