As discussed here, to form a team/crew there must be at least two members in it (creator + new member).

To join a team/crew, PM the creator about it first. If it is agreed that you will be a member you or the creator (or both) can post your addition.

Don't be afraid to try to create your own if you don't find a team/crew you want to join or you just want to have your own team/crew.

An added feature that has just been made available is the hidden team subforums. Now, teams can discuss/share any information within their subforum without others (besides me) seeing them.