@Daniel Lochen, I own a small office building in a town of 20,000 in Maine. It has four offices and was vacant when I purchased it. A couple of thoughts and best practices:
1) I use the same lease for all tenants
2) I offer a 1-year or 5-year lease. Smaller annual increases are built in to the 5 years lease. 3 of the 4 current tenants are on a 5-year.
3) Additional parking spots are available.
4) To sweeten the deal and make it easier for tenants to select my building, I include all utilities.
5) Tenants expect the rent to go up every year, and so I don't disappoint them.
6) If you need to renovate, keep it simple and cheap. Light, neutral paint colors. LED lights.
7) Does the building have a shared bathroom? That's ideal if it does. Make sure it looks decent. For a couple hundred bucks you can get a new toilet and vanity. Some bright lights and a coat of paint will make it look great for under $500.
Message me and I'll send you the lease. It's based on one that I signed when I used to lease space and has served me well for the four years since I purchased the building.
Hope this helps,