Storage can involve several components that can deteriorate and lead to related damage if not maintained.

Battery:  The battery should have a trickle charger so that it is actively prevented from losing its charge. Modern cars have computer components that use battery power while sitting. Over several weeks these computers may draw enough to drain the battery if there is no trickle charge being applied and if no one runs the engine every few weeks to charge the battery.

Oil:  The oil should be recently changed. Do not store the car with old oil, planning to change it when you take it out of storage. It is important to have the engine sit with clean, uncontaminated oil during the storage period.

Gasoline:  Run the fuel down to less than one-half a tank, pour in a gasoline preservative, and fill up the tank just before storage. Gasoline preservatives are available at most auto parts store.

Facility:  Store the car in a clean, bug and rodent-free, secured garage facility. Some reasonable amount of fresh air flow is desirable. Crack open two windows just to allow fresh air to circulate.

Starting:  It is desirable to have someone start and run the engine for several minutes about every three weeks. This will allow all fluids to flow through their lines, prevent moisture and contaminant build up in the oil, and help keep seals tight and leak-free.