It's a bit like being an extra in film and television. You don't really become a member of the Crisis Actors Guild (CAG) until you reach a certain amount of appearances, screen time, or voice parts. Most crisis actors and actresses spend time working other jobs between bit appearances while hoping to get their big break.
If you want to break into the industry, then I would highly advise getting a crisis agent to keep your name and comp card circulating in case any new opportunities arise.
(Edited 3 minutes later.)