I recommend some prelim poking around first.. find out how other facilities in your area are doing. What is their occupancy rate? What is the unit mix? What are their rates? Are any of them expanding now? Do they have room to expand in the future?
Next... consider your property. Is it highly visible? Location is HUGE in self storage. Access? Zoning?
Next.. money and financing. As you put your deal together - you will be considering cost of construction, site prep, fencing, onsite signage... and you want some reserve cash to carry you during the lease up phase.
There are different options when it comes to financing. During your construction and lease up phase, you are likely to get a bit of a higher rate. Local banks are great for this. Do you own the land, or have a lien on it? If you own the land, financing ought to be pretty easy. You want to show 60 to 70 LTV and 1.25 to 1.3 DSCR. Once you are through the construction and lease up phase you can shop around for perm. financing. If you loan will be for 1 million or more, you have more options - and better rates... 6% plus or minus a hair.
www.selfstorageguide.com is a great resource.. they have a forum. Nice to have people there to answer questions like
"what do you do when someone kept a snake in the unit and it has 300 babies?"