These can come from family, friends, business associates or your social network. I have done over 25+ real estate deals with family or friends that have referred me to others. You can use things like a bi-monthly newsletter, e-mail marketing or direct mail pieces to keep you in the back of their minds and have the conversation remain open. Rewarding referrals with a monetary bonus when the deal closes is also a great incentive for them to keep their eyes and ears open for you.