Assessing Debt Risk before acquiring another rental

[Gareth Fisher]

I'm in the process of deciding if I would like to acquire another rental property or pay down more debt.    What metrics do you prefer to use when assessing the risk of adding more debt to your portfolio? 

Thanks in advance.

[Thomas S.]

If it is a positive cash flow property I see little to no risk adding more properties. Assuming of course you have reserve funds.