Youth need to be in charge of their own projects and programs and need to be trusted to execute the event themselves. Make sure the adults are in the background and not taking the work, limelight or credit from the youth. From the beginning insist that it is the youth's program and it will fail unless they step up and take responsibility for it. Remember that they will probably do everything last minute, so resist the temptation to step in and do it for them. If they do it themselves (from their perspective) they will feel good about themselves and each other and have a common experience to bond them. It is one of the best experiences you can give them.