Options for getting investor's money back

[Khouri Rice]

I am going to be purchasing 4-6 homes free and clear (for around 10-20K each) that already have good tenants/leases in place through the middle of next year (2014). I am getting the money loaned to me by a close friend/customer (50K total) who is only looking to make 10% on the loan for a 12 month term (55K payback December 14). My question is....after I take ownership of the property what might be the best way for me to use the properties to take money out of them to pay back the loan, and maybe use some extra to purchase more properties or do work on these to increase rents/value. Each house is appraised at around 45K-60K.