Leave it in a good state
It is a good idea to leave your motorhome in the best state possible, even if it will not be driven or lived in for several weeks or months. Check its mechanics are working properly, the tyres have good tread and the electrics are ok.
You don’t want to find things have deteriorated when you pick it up again just because you had not looked after it properly beforehand.
Clear it out
Empty the water system, including the heater and toilet, remove everything from the fridge, turn the gas bottles off and clean the cupboards thoroughly.
You don’t want to attract mice or rats to the caravan by leaving food or waste, and you could damage your tank if you do not drain all the water out of the vehicle.
While it is prudent to choose a storage centre with CCTV cameras to deter any thieves, it is also a good idea to mechanically secure your vehicle too. Fit wheel clamps, foot pedal locks, steering wheel locks or gear locks to make it even more difficult to steal.
You could also install an alarm or immobiliser, which will be a further deterrent for thieves.
It is wise not to leave anything valuable inside the motorhome either. Even if it is difficult to move, doors and windows of caravans are not the sturdiest and burglars could target motorhomes simply for the possessions inside of them.