Licensing (for a regional license) is very different between the SCCA and NASA.
The SCCA allows either of two routes: You can complete an accredited racing school (check their list for accepted schools), get your physical exam and go racing; or you can obtain a novice permit (requires physical exam), and complete two SCCA drivers' school weekends and two regional races as a novice. You'll then get signed off and receive a regular regional license. This "fast track to the racetrack" does allow quite a few onto the racetrack that have no business there, however.
I like NASA's approach better. You have to first work your way up through four levels of HPDEs (track-day run groups), each with different constraints regarding supervision/passing, and you must be checked out to advance to the next level. Once you've reached HPDE4, you can be accessed for a competition license, depending on what form of racing you'll be doing (whether it'd be time trials or wheel-to-wheel).
NASA's licensing does a better job of filtering out those that do not belong on the racetrack, and they draw a hard line regarding contact in all classes; it still can and does happen, though. The SCCA seems to accept SM as a high-contact race group, and my experience is that little will ever be done to change that aspect; bring a trailer and a broom. If you will be working on and maintaining your own car, you might give some thought to that.
Dave Stine
"America is all about speed. Hot, nasty, bad-ass speed," -Eleanor Roosevelt