Re: Fans
 

I agree, we advertise openly to our student body (our school is about an hour away from the NYC regional) however not many people are interested enough to come.

We had a couple of members last year who brought their boyfriends/close friends along, and they seemed to be enjoying it.

I think one of the best ways to get people interested in FIRST is to bring them to a regional, particularly on the last day, when the competition really heats up.

Re: Fans
 

As a mostly uninvolved alumni, I (and some friends) came and watched GTR in 2005 and Waterloo in 2007.

This reasoning is based on the idea you've brought a dozen or so people from your high school who have no relation to the robotics team but may be somewhat interested (i.e. not just there to miss school):
I think one problem is that unless you're at a super-regional (the few years when GTR ran double-field), your team isn't up often enough to keep your fans entertained. For the core team, there is always scouting, repairs, preparations, strategy, finding and talking to your alliance partners, etc. You're never idle at a regional. However, for the people from your high school who came to watch, they get to watch a single 2 minute match every 40 minutes. If they go back and say it was the most boring thing they've ever seen, it'll hurt your recruiting efforts in the future. But if each match is exciting to them because they know what's going on.

Based on this, it seems like it'd be important to keep them entertained and informed. Have someone charismatic from your team dedicated to telling them when the next match is, have them analyze the previous match. Maybe they could use some scouting data and give a pre-game preview of the next match, tell your fans what to watch out for. Field some rules questions they might have.