Don't store any sort of food items in a storage unit as it will attract rodents.
Don't leave paints, oil or gasoline in your storage unit. Drain all gas and oil from lawnmowers, blowers, etc. It is against the law to store hazardous or combustible materials such as these.
Don't give anyone access codes or keys to your storage units.
Don't hesitate to ask any facility manager any questions you may have before or during move-in.