As with residential real estate investing, the number one criteria to look for is Motivated Sellers. And for commercial real estate, the motivated sellers are banks and mom & pop organizations. The money is to be made if you can identify the problem (find out why they are motivated), see if you can fix the problem, fix it and it usually increases the equity right away.
In addition, if you can find a property in the path of progress (ie, new home depot coming soon), you will have a good holding property with great appreciation potential. Investors can find out about any new development from the city hall's planning department. Also look for revitalization zones that the city plans to invest money into. Usually, there will be grant money available for investors to go into these areas to revitalize the area.