Change the oil. Keeps the carbon/acid in it from eating on stuff while stored.
Wash it. Bug fluids will eat at paint during storage.
Up on stands. Stops tire rot and keeps tires from flat spotting, especially if you have anything with bias ply.
Battery tender on.
Fill tank, add fuel stabilizer and run some through the engine.
Especially if you store outside:
If you've got some paint on metal and/or chrome, put some wax on it but don't buff it off. Leave it until spring. Stops rust.
Pull plugs, add small amount of oil and crank without starting a few revolutions, reinstall plugs.
Put vaseline on anything prone to rust. You can also put vaseline on your wanker, but wipe it off...........
....with long smooth strokes.
Leave plenty of room around your bike(s) so you and your buddies can stand around, drink beer and talk about riding while there is snow on the ground.