Many of us don't drive the motorhomes in the winter, and they sit for months. The first thing that sticks out in my mind the most, is corrosion to battery cables and other high amp connections. Before taking it out in the Spring, clean all the battery cables and other high amp connections ( such as to solenoids and relays ) Nothing more annoying than a bad ground connection, caused by corrosion somewhere. Causes lots of things to quit working.
The other things can be prevented somewhat, like old fuel, or plumbing problems. Proper fuel additives like Stabil, before storage, or whatever to prolong gas life ( or diesel life ), and proper draining / winterizing of fresh water components. Ruins your day in a hurry to discover a leak in the pipes from freezing. :-)