Researching Rental Incomes

[David Rodriguez]

Hello Everyone! I'm looking into acquiring my first real estate properties over the next few months, and have begun looking at my local markets. The thing I have run into, mostly due to my inexperience, is how to estimate what rental incomes I can expect for a Buy and Hold investment. I'd appreciate any help with the following:

What are the best ways you have found to research local rental incomes? 

What is your criteria for rental income to home value? (I understand this is something market specific, i'm just curious what other thought processes are out there)