The two most important things to do, when storing your bike, are changing the oil and stabilizing the gas.

Replace the oil and filter.  Used motor oil contains impurities that can cause corrosion within your crank case.

Fill the fuel tank to the top.  If any air space is left in the tank, moisture will accumulate and form corrosion.  This will cause clogging of the fuel lines, fuel pump, carburetor and fuel valves.

Add a fuel stabilizer.  Stabilizer can be bought at most motorcycle shops.  Fuel left sitting for an extended period will separate and deposit a gummy varnish that will clog just about everything that comes in contact with the fuel.  Run your bike for 10 minutes to get the stabilizer into your carburetors.  In the spring, drain the fuel and use it in your car or lawnmower.

Store the Battery. It's best to remove the battery and store it in a cool, dry, well ventilated place.  Don't place the battery on a bare concrete floor, sit it on a piece of wood or styrofoam to insulate it from the cold concrete.  To keep it's charge over the winter, attach a trickle charger and turn it on every once in a while.  This will keep the battery in tip-top condition.

Stand your bike on the center stand, ensure the tires are at their correct pressure and cover the bike to minimize dust accumulation.

Good luck, and I'll see you in the spring.