Starting a Rental Agency

[Andrew Urban]

Hello,
I hope this is in the right forum. I looking to start a rental agency in my state or RI. I know that you need a Realtor license and starting and LLC would be a good start. My big question is how to go about obtaining properties to rent? In the past is has been word of mouth and a little luck with people contacting me for something else. I have contacted a few landlords from craigslist, but most of them are upset that I'm calling to offer my services and not calling to rent their place.
What are you suggestions to obtain properties for renting? Thanks for the info.
Andrew