If you will need to access your possessions frequently, choose a storage facility that is either nearby or on the way to a frequent destination. If you will not need access to your stored items often, you may be able to find a better value a little off the beaten path.
Avoid a facility that is in a "bad part of town".
Decide how much security you need for the items you will be storing. Then evaluate the security measures the storage facility employs. Is the facility fenced? Does it have surveillance cameras, electronic gate, etc.
Do you need a climate controlled unit (heated in the winter, cooled in the summer). Most items do not need climate control, however, if you have items that will be damaged by humidity or extreme temperatures, you might want to consider paying the extra $$ for a climate controlled unit.
Does the storage facility look like it is being cared for?
Is there overgrown vegetation against the facility walls? Vermin love to hide out in vegetation.
Are the parking areas maintained?
Are there pest control bait stations around the facility?
Do you want / need 24 hour access to your storage unit. Might you need something from your storage unit at 10 p.m. or on a Sunday?
Decide whether you need a climate controlled unit or not -- expect to pay 20% - 50% more for climate control.
Decide what size unit you need. If you will need access to your stored items, you'll want to leave space to move around in your unit. For a large unit, consider leaving a center aisle down the middle of your unit. You can pack the unit solid if you will not need access to your possessions until you move out.
Use this storage space calculator as a general guideline for determining how much space you need.
Be sure everything you pack is clean and dry to prevent mildew.
Don't pack your storage unit in the rain (see above)
Try not to pack your unit when the ground is wet - that water on the bottom of your shoes will be tracked into the storage unit (see above)
Number or label boxes for easy identification
Use quality boxes and always pack them completely so they don’t collapse when stacked.
Clean all appliances thoroughly before storing them.
To save money on all packaging materials, ask your moving company if it sells or even gives away used packing materials.
Reduce the number of clothing boxes by keeping soft items such as clothing, socks and undergarments inside dressers during the move.
You want to make sure, if space allows, to leave an aisle for easy access to the items in the rear of the unit
Place items you are going to access the most in the front of the unit, and the ones you will never need during your stay, in the rear of the unit.
For security purposes, place the most valuable items at the back of the storage unit.
Shelving helps to maximize the access of your items.
Leave air space between items and the walls for ventilation.
Always put the heavy items on the bottom and light or awkward items on the top.
Cover furniture with a dust cover or sheet.
DO NOT store food. Mice will find the smallest quantity of food and they can easily chew through plastic.
Do not store flammable items such as fireworks or gasoline.
Don't pack it and forget it. Visit your unit periodically to check the condition of it and your possessions. Over a long period of time, there will be dust and cobwebs -- sweep out the unit occasionally.