What's the best way to accurately predict rental rates?

[Matthew Espana]

Hi all, 

I am looking to get started investing in long term rental properties. However, when analyzing deals what seems to confuse me most is determining accurate rental rates. Zillow offers Zillow rents, but I don't know how accurate those predictions are? Furthermore, in the area I'm looking to invest in, most zip codes have both very nice and not so nice parts of them so looking into the zip code does not feel as secure either. Can anyone offer any tips or advice on they're most sure what a house will rent for? 

thank you!