Generating leads, IMHO, is the hardest part about being a loan officer. Once you find a niche or a system that works well for you - you're set. I'm sure others will chime in about buying leads, so I'll leave that alone, but I will say that you have the right idea when you mention having a "carrot" to dangle for real estate agents.
My preferred niche is
for sale by owner marketing to get some of these "carrots", but there are a variety of
realtor marketing systems available out there that might be worth looking into as well.