Hey there!! nice ta meet ya! glad to see another junior here, and with such a great idea!! I've worked with my model club's kid build project for 2 years now, so maybe I can help. let's see...
set up a time schedule. my group meets once a month. check which days are most convienent for your group.
set up a time-table for meetings or gatherings. i.e.- starts at (whenever), first orders of business (i.e. projects, group builds, contests, meeting schedules, please would someone contact such-and-such about whatever, sort of the club's political aspect if you know what I mean.
maybe you could set up something like a government , with a club head, a second in command for whent he chief's not there, a treasurer if you'll have a member fee or something, stuff like what you had for a class government... (if you do create a government, dont forget to involve all the members in it, like by having votes on certain topics or elections) ( by the way, no, im not on a crusade to spread democracy everywhere, its just an effective form of governmen in this case). this might go along with the government of the club, having certain age members, elgiible for certain positions in the group. I'd guess this also goes along with the whole leadership ideas that such paramilitary (for lack of better wordage) try to build in their members (another good reason for the club, to explain to your superiors in your RCAC group) like the scouts and CAP in the U.S.
set up some rules and regulations. no stealing, inappropriate actions toward another member, damaging another's models, along with the consequences of such infractions. suspension, monetary fines, community (club) work (i.e. must help in setting up contest or meeting rooms, cleaning up, etc...)
make sure to have emergency supplies with you for injuries, adult help nearby or within contact. if the clubs within your cadet group (i think we call it CAP, Civil Air Patrol, here in the U.S., but don't take my word on it...) then you might have adults and emergency stuff around.
having some adult supervision is always a good idea. just for assistance in control, medical emergencies, assistance with whatever. have the older members be responsible leaders. make sure that they help the younger members in builds and such.
you might like to set up things like badges for group builds, and awards for contests, to promote the members to stay with it. (again something where having a government with a treasurey would greatly help. sales of some kind, dues from the members, would probably help in paying for such things, and the government heads could organize it)
I hope i didn't overwhelm you with this stuff. its up to you if you'd like to implement it. maybe your groups not big enoguh right now for a government to even be necessary. These are just some of the things that appear to be good aspects of my groups organization. hope you find at least some of it helpful.
see ya round the forums. and good luck...