Our school district actually has a science discovery night where students in grades 6-8 come and check out what different extra cirricular activities are available at the middle school and high school. We bring a robot with us and show them what it can do with some videos on display and some demonstrations. Our robot is on it's way back from the championship right now, and the event is this week, so we are a little disappointed because we feel like breakaway would be the perfect game to get kids interested. We usually steal the show anyway though because kids are like, "ooooooooo look a robot! Did you make that?" and then they stare at us in awe because they cannot imagine making something that awesome
(that was me four years ago)
you might not be so lucky as to have a recruiting opportunity like that, but it helps to look for different ways you could show off your robots in public where there is a strong possibility of potential members getting a chance to see your robot. Also, I have heard of other teams asking I they could bring the robot into classes to recruit members, which I could imagine being successful.