I have a lot of luck approaching real estate agents at open houses. Target the agencies that don't have in house lending first (ReMax, etc) Just drive around and find an open house with very little to no traffic and head on in. I just introduce myself and ask who they work with in regard to mortgages. How do they like them? If the experiences have been bad, ask them to give you a shot. If they have someone they like, I try to find niche products not many others have access to, such as 203k streamlines, Homepath, VA, and USDA.
From there, you need to follow up weekly. Just a quick call or email. They are no different than any other customers and you need to stay in front of them if you want to earn their business.