Your storage area should be free of mice. If you're not sure that it is, put some traps or poison underneath the bike. Mice love airboxes and the taste of wiring harnesses. Also, select a low-traffic area where your bike isn't going to be bumped into by you or anyone else on a regular basis. Next, throw a cover over your bike.
Many people believe a plastic tarp is best, as it keeps moisture out.
But the problem with these tarps is that they don't breathe. Moisture in the air gets trapped underneath and builds up until it falls on the bike, causing corrosion. Save the plastic tarp for underneath the bike, where it can be used to block out moisture that rises up from the ground - even through concrete. When the calendar finally rolls around, and it's time to get your bike out of hibernation, you'll be glad that you took the time to do things right. I like to change the oil again in the spring, as it can absorb moisture over the winter.