1. Talk to rental property owner over the phone, don't use solely email.
2. If possible, arrange to meet the owner at the property.
3. If you're not able to meet the owner at the property, get documented proof (i.e. utility bill) that proves he/she is the owner.
4. Ask for references from prior renters and/or check online reviews.
5. Do a Google search of the owner's name, his phone number, email address, and the property address. This could unearth complaints or other information about the rental property.
6. Before paying, get a copy of the rental agreement and read it thoroughly.
7. Try to pay using PayPal, credit card or check. Avoid paying by wire transfers.