Well, I'm mad I didn't think of it myself, but I would be remiss if I didn't share this resource with others. What is it? It's InsideLobbying.com, which houses a series of short videos on how to have an effective meeting with members of Congress. It includes preparation techniques, why advocacy is important and tips from insiders like actual legislative staff and members of Congress. There's also a whole page of useful tips on the site on setting up meetings and preparing to deliver an effective session.
Check it out!