If the market is tough, I reduce the rent rate over the full 12-month term.

It's an estimated cash on cash return given current rental rates subtract expenses assuming 7% interest rate, 10% management fee, 5% repairs, 5% capex and other expenses like mortgage, insurance, tax. it's a estimate to tell you what properties to analyze vs ignoreyou can see the are pockets of negative returns as well as pockets of positive return. this is to supplement the data @Devin Conley provided

Live in one unit - It's a great strategy when using a bank for financing as the down payment and interest rates are more favorable to owner occupants.  

Quote from @Elinore Aguilar: The best way is to have the best firm with a reasonable rate and trust reviews.

But I did not like what I saw, anything under what Costar would rate 4 stars did not appeal to me. 

There are many investors that look at promises ROI or interest rate and nothing more.  

And, analyzing ROI, CoC, and rent vacancy rates, etc are all manual. 

It earns a great rate of return compared to a bank account and is fairly liquid.

Or put in your interest rate here, and your loan balance there.The art is where I think most people struggle, and I don't think this can really be done without real world knowledge.  

You can often get better rates with a national lender, but the customer service is non-existent, communication probably sucks, they may ask for the same documents multiple times, etc.