Pretty much what they said. A slightly modified Geezer list:
1) Take one final ride for the season and while out get...
2) ... a fresh tank of gas, use Stabil or whatever brand you like. A full tank prevents rust and corrosion. In addition, a full tank doesn’t let air in where it can condense water into your tank.
3) While your bike is warm from your ride change the oil and filter. Acids build up in the oil when you ride so the oil change prevents your engine parts from stewing in bad stuff over the winter.
4) Periodically trickle charge the battery or hook up a battery tender. A charged battery won't freeze and keeps it healthy. The ECU takes a small but constant current draw from the battery. If the battery is allowed to become significantly depleted while the temperature is around zero degrees (F) it can become permanently damaged.
5) During the winter move the bike forward or backward a few inches about once a week so the tires don't develop a flat spot (you are allowed to make vroom, vroom noises while you do this). Or, use the center stand and something like a jack stand for the front end to get the tires off the floor. If your tires are going to be on the ground you may want to put something between ground and the tires.
6) Depending on what your situation is, you may want to cover the exhaust pipes but more importantly, cover the air box opening to help keep the little critters out. For some reason mice seem to see air boxes as a perfect mouse house.
7) It wouldn't hurt to wax the bike to protect the finish from the condensation that happens in early spring. A cover is a good idea.
8) If you have added *straight water* to your overflow bottle have your antifreeze tested for concentration. One of those little squeezie bulb thingies with the floating beads work just fine. Most auto parts stores have these testers and they are inexpensive.
9) Do not, do not, do not, do not, do not, do not periodically start and idle your motorcycle.
10 Pray for an early and nice spring.
Zones 3 - 6 need more stringent preparations than zones 7 - 10.