Good question - If the property is already zoned commercial, you've already passed the first (and sometimes biggest) hurdle. Before you buy the house, check with the current owner to see if the house has a "CO" (certificate of occupancy). Without the CO, nobody will be legally allowed to occupy the property without an inspection. If the property is dilapidated, you'll most likely need to bring it up to code. You'll also want to check with City zoning to see if there are any other things that must be done to the property before leasing to a commercial tenant (think ADA, etc.).
Best of luck!