First rental what to know how you do numbers

[Kurt Haines]

I have done several flips but never a rental. It's a older condo that I can pick up for 10,000 and there is a tenant that has been there several years month to month for 550. Here is the two thing that worry me. There is no HOA fees cause there is no HOA in place anymore. There also no paper work from the owner how much they are spending each month. I look at it and it is in decent shape. How would I figure roi? And should I worry about the HOA?