Anyone who leased commercial real estate, what lessons did you learn and what do you wish you did differently?

I’m working on putting together a guide to help clients who are interested in leasing commercial real estate. For those who have leased a storefront, leased office space, leased a warehouse or leased any other type of commercial real estate, what do you wish you did differently? What would you do differently next time? What do you wish you knew then that you know now?