I have stored bikes long term before, and have pretty much perfected a system that works. This is if you do not plan on starting the bike until you take it out of storage. First, it needs to be stored indoors. Outdoor storage will destroy a bike.
I warm up the engine, and change the oil and filter. I then drain and remove the tank, make sure you get all the gas out, then pour in about a qt. of WD-40 (I buy it by the gallon), shake the tank good to completely coat the inside, then drain out the excess. You can still use it as WD-40. While the tank is off, drain the carbs, fill with WD-40 through the fuel line, then drain that out. Tighten the drain screws, put the tank back on, and hook up the fuel line. Remove all the spark plugs, and using a transmission funnel, spray some fogging oil into the cylinders. With the bike in gear and on the centerstand (for the VN750) turn the rear wheel, which will turn the engine over pretty easy if the plugs are out. Put the plugs back in finger tight (for the VN750, you actually only need to remove 2, I'd remove the 2 non recessed ones) Air up the tires to the max pressure on the sidewall. Remove the battery, and connect it to a battery tender. Do not leave it in the bike, even MF AGM types can leak acid. Remember, the battery will still be wearing out, you can't make a battery last forever, even if it is kept fully charged. Throw a sheet over the bike.
About once a month, remove the plugs, spray in some more oil, and turn the back wheel just a bit. The idea is to keep the cylinder walls lubricated, and keep the piston rings from sticking in the bore. By using the back wheel to turn the engine over, you are also turning the final drive, clutch, and transmission. Parts that are designed to be moved need to be moved. Keep the tires inflated, move the front tire to a new position to prevent flat spotting the tire. Put the plugs back, step on the rear brake to work the mechanism, squeeze the clutch lever and front brake lever and twist the throttle.
The 2 biggest dangers to bikes that are stored for long periods of time are the pistons sticking in the bore, and oil seals drying out and leaking. Moving parts with oil seals, like the final drive, helps protect them. Working the shifter up and down once a month wouldn't be a bad idea either.
This may sound like a lot, but it really isn't. It takes less than an hour the first time, and about 10 minutes a month. How much is your bike worth? Even my crappiest one is worth more than that.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike