It depends somewhat on where the bike is located, what type of fuel is available, what atmospheric humidity, condition of the points, condenser etc. Where I live, they put ethanol in the fuel which can cause big fuel problems over the winter as the ethanol attracts water, corrodes plastic fuel lines, and is generally a problem. I try to get the ethanol out before storage. Wash the bike, If you have real petrol, top up the tank to remove any chance of humid air getting into tank. Turn off the fuel petcock, start the engine until all fuel is out of the carburetor. Change the oil and filter, lube the cable lines, top up the fork tubes and primary box, put air in the tires, charge up the battery after checking the battery electrolyte level. Fogging the cylinder with oil can't hurt as every cylinder head I have taken off has a few drops of water in them (and I live in the desert, God only knows what it is like in a humid climate). I then put a "battery Tender" float style motorcycle charger on the battery (check water level once a month to make certain the electrolyte has not boiled off). Put bike is a garage or covered dry shed, place a breathable cloth (like a bedsheet) over the bike to keep dust off and allow any moisture to evaporate.
That's about it, this works good for me, bike starts well in the spring.