Not getting into every aspect of recruitment, the most effective methods we have found for requirement is to do in-school demonstrations. What I mean by that is going into the classrooms and demonstrating the robot to the students. I have found that it really gets them excited about robotics, and really rallying to join.
Another thing we have found useful is making videos for announcements within the school. The video is short, and basically makes robotics seem like the coolest thing ever. Don't forget to mention how well you did, since kids like to see good stats from their school's team.
These things, along with our community involvement, have brought us in about 15+ persons a year for the past few years. It also helps to get school involvement.
