You pre-screen and eliminate low income tenants by phone or email and they never set foot in the rental or get an application.

Screening is essential; if a tenant seems too good to be true they won't stay long, we have the best luck with people who already have roots in that neighborhood.  

I have learned a hard lesson about screening my tenants and will be doing a lot more thorough screening for the future.

This should cost under $300.Next, like all rentals, you will want to be sure to screen the prospective tenant/buyer thoroughly.  

After some thought, I think accepting roommates would be fine as long as I screen each of them separately and make sure each of them meet the requirements (income, etc.) on their own.

Cut out any un necessary expenses.

You could see how they market, how they screen the lead, how they know what lead to pursue, how they talk to sellers, how they negotiate with sellers and buyers, how they built their list of real buyers, how they have a relationship with title companies/closing attorneys, see how they build relationships with realtors, contractors and other professionals, see how they do the paperwork, how to handle problems when they come up, how to know what leads that are a no for now, but they know that one they should follow up with a month, or so, later and everything else that goes with the business.

On the supply side, you will eventually see flakes of rust and particulate in the screens on faucets.  

You will also see opportunities that won't show up on an excel spread sheet or computer screen. 

A project manager would be involved in rehabbing, but unnecessary if you're doing just a few a month.