Homework that needs to be done before i buy my first MultiFamily in San Diego

[Namal Burman]

To all my BiggerPockets friends. I have 3 ( 1 condo +2 townhome) rental and one primary home (single family ) all in San Diego and for my rental portfolio of buying with my own money i am done. Next goal for me is to do my first multifamily( 4 unit) deal in San Diego either through 1031 exchange of my condo or  (my cash  + friends cash). What homework i have to do so i be ready in next one year? Real estate i know is all about location/location/loacation . For multifamily i know location will matter/ rent would matter/financing would matter. What else if any one has a nice flow chart and guide me i will appreciate.

Regards,

namal