In my business, as a Home Inspector, I get a lot of work from Realtors.  When I inspect a home, there may be a stack of Business cards on the counter from Agents that have shown the home.  I used to take pictures of these and send a quick email to introduce myself and offer my services.
Another tactic I used when building my business - drop off snacks and water at open houses that Realtors hold.  It's a great way to introduce yourself.  Just be sure not to interrupt, wait until visitors are gone.  Good Luck!