@Matthew Wright
These are all great questions and the answers revolve more around personal preferences, capabilities and risk tolerance instead of a good hard “rule of thumb”. Like in multifamily we like properties that are lacking, meaning the "less" a facility has the more potential value add I see. So things like no security, no online presence, bad management are all things I'm looking for.
I have found that many people entering storage haven’t truly thought out their road map yet. They have heard storage is great, but one area all lot of people haven’t thought of is how they plan on financing it. Someone can find a multimillion dollar deal but with no prior experience in storage specifically, they can’t get a loan to fund it. So before asking yourself how many units or how many square feet (minimum 12,500sf by the way), ask yourself questions like: how much time do I want to put towards this? If I find a deal how am I financing it with no prior experience in this asset class? What are my capabilities to add value and compete in the marketplace at this point?
I started with no money or experience so raise a bunch of family/friends money and took down a small mom/pop facility. I put in all the work and ran it. Everyone understood it wasn’t going to make anyone rich and it was more of a proof of concept. It allowed me to get my hands dirty, establish systems/processes that are now scaleable and gain experience. Now return to my own questions I now have the experience, capabilities and ability to obtain financing to move up to a larger facility.
Hope my rambling helps. Feel free to DM with any questions.