Introduce yourself: A reporter can't come to you as a source if he or she doesn't know who you are! Introduce yourself to reporters and explain that you are always available as a source should they need one.
Make yourself available: A common problem that arises between reporters and expert sources is availability. If a reporter comes to you with a story and asks for your expert opinion, make time for it. Otherwise, the reporter may get the idea that you are not available as an expert source and seek elsewhere.
Take advantage of follow-up stories: Reporters are often on the lookout for follow-up stories. Look for good angles for a follow-up story to suggest to a reporter. This not only helps out the reporter, it also gives you the perfect opportunity to chime in as an expert source.
HARO: Otherwise known as Help A Reporter Out. This service was specifically created to connect reporters with sources for stories. Emails are sent out 3x a day full of requests from reporters for an expert source.