From what Ive learned through the yrs...the best way to store a vehicle, under a shed or even indoors, that will be out of service for 6 months or more is a follows:
Remove the battery, test it, and place on a trickle charger indoors
remove the carb, drain it, and wrap in plastic bag tightly
remove all the plugs and fog all the cylinders with marine fogging oil or marvel mystery oil. I plug them with blue shop towels rolled into a tight knot.
Drain coolant, flush system and blow out any moisture remaining with compressed air.
drain gas tank and flush it, or fill it to the tip top, but i prefer to drain it
drain the oil and add a few quarts of kerosene to remove any sludge, leave in till you are ready to refill with oil, then drain it out
jack up the car and put the frame (or suspension on unibody cars) on blocks or jack stands to prevent flat spots and dry rotting of the tires
cover the car with a large old cotton sheet and put a few mice traps under and around the car. Yes, they will get into your car if you don't kill them first!
place a catch tray under the trans (auto only) to catch any seeps, or drain it.
Its a lot of work, but if and when you plan to sell it or drive it again, it will be a lot less of a pain to get it back on the road quickly when the time comes. Some of these steps can be skipped, but the one I would be sure to do is remove the carb and draining the tank.
Bill