My business partner and I are looking to do our first commercial deal (and my first RE deal). I'm a financial counselor with a background in tax and investments, and he runs his family's property management company that is capable of servicing and managing sizable commercial properties (they currently service a few fortune 500 corporate campuses in the area). He also owns a duplex in Boston that has been a home run. We could come up with money for a down payment that would involve HELOCs and rainy day funds, but we would prefer to go OPM.

Ideally we want to purchase a small commercial office building around $1m and leverage his resources.  We can manage and improve at a reduced rate.  If not an office building, perhaps a 6 - 8 unit multifamily. 

Any tips for first time commercial investors without money down, specifically in Boston suburbs? Could we do part friends and fam OPM with the rest as a mortgage? If not, could I use a HELOC as a down payment and mortgage the rest?