We've had some great success with our summer camp. We hold it every year, and advertise it in a newsletter that goes to the families of incoming freshmen (I think its sent out May/June-ish). Camp just started this week, and we have have 6 freshmen. For what I think is the third year in a row we even have an either grader as well!
The camp is designed to be fun and to pull everyone into what FIRST is all about. The get to build stuff, show it off, and overall everyone seems to really enjoy it every year. And when it comes to recruitment... well, if we can get them to come to camp, they usually stick around with the team once we start up in the fall
