We have dealt with this issue for years, and I think we've finally optimized it for our group.
We have an open fall, in which our "varsity" students (the veterans, especially those that have lettered the previous year) do specific training events (such as retasking the previous year's robot) and serve as mentors for the new students, the "JV" squad. JV participates in BEST robotics as an intro to the six week build, the design process, etc. There are no tests for incoming students, and everyone who shows interest is accepted as part of the group, though the "team" is yet to be established.
After BEST is finished (end of October), all students are brought together and given the expectations for participating as part of the "team":
- daily meetings, including Saturdays
- specific skill training sessions
- fundraising
- participation fee
- participation in a serious off-season build
- training in FRC history
The students who stick around become the "varsity" team, and have the opportunity to letter.
We've tried many variations, and this seems to be the most effective. The least effective was to have a "team" and a "club" at the same time. The club students felt second class, and we had a lot of conflicts. Hope this helps some.