When I practiced law one of my most successful business development efforts was to identify a potential client problem before my competitors (and the client), offer a solution and give it away. Yes, I said “give it away.” I created guides or conducted workshops on whatever the hot topic was.
I am not sure I knew it at the time,but I was influencing by the law of reciprocation. That means when you give something away, the person who received your help, will more likely think of you when they need a lawyer. I first learned of the rule when I read Influence: The Psychology of Persuasion by Robert Cialdini. The very best way you can use the law of reciprocation is to help your potential client or referral source get some new business.
If you want to learn more watch this short video clip.