The most important ability you start with is the Perform for Tips interaction. This will be your main career builder, and you'll need to do it until level two when you can get a gig at the Coffeehouse in town. Perform for tips is always a good way to improve your level while waiting on gigs to start. Perform for tips in well-traveled areas like the Park and Theater at night.
Here is a table showing all of the levels, weekly stipends, new interactions and magic tricks, and when you can audition for gigs at the various venues: