OK... here's an answer from someone who still knows what winter is!
-35, 5' of snow in the yard, and not a snowballs hope in hell of riding anything except a snowmobile in the foreseeable future.
Here's my list in no particular order:
Weight off the tires (centre stand is sufficient, side stand is not)
Bike is washed dry and waxed
Lube all joints
FULL gas tank with stabilizer, RUN IT THROUGH THE CARBS! In the spring I drain this out for the lawn mower and fill with fresh.
Fog the engine with engine fogging oil
IF you get water in your garage/shed in the spring put the bike up on blocks to keep it out of the water (see pics

)
Block off the air-intake so mice don't nest in the air-box...don't laugh... they will
Block off the exhaust pipes for the same reason
Pull the battery, put it in your house on a trickle charger for the duration (do I have to tell you NOT to put the battery on the concrete floor?)
A mist of WD40 or other spray lube on corrosion susceptible parts is recommended.
Cover bike with a good quality breathable cover
