it all depends on your risk profile. I run beginner (have for 3 years now) on bone stock street bikes (minus mirrors, taped lights etc as per the manual). I dont know what your plans are e.g., intro day or full B day, but B class is about 1/3 pure street bikes - 1/3 street with track doo-dads, and 1/3 full on trackers.
The sport has inherent risks, but based on most of the crashes I have witnessed, a good portion of them can be described as "too much on cold tires" type incidents - too much throttle, too much brake, too much lean angle etc... basically being sloppy and/or asking too much of cold tires. While not completely avoidable, you can help minimize your risks of crashing by (in no particular order):
1. slowly building speed, while your tires warm (usually 1-2-3 laps, depending on the track)
2. building confidence while you build your skills - be smooth on the throttle, brakes, steering etc - anything abrupt is asking for trouble
3. working with control riders to develop your skills, while NESBA isnt a school, there are lots of people (especially CRs) that are here to help, give advice, work to provide a safe environment etc
4. reading and re-reading the manual to ensure your bike, gear and mindset are all aligned with the expectations and requirements of the club.
5. if unsure, ask questions - there are 2-3 months to go before the season kicks into high gear. Not sure where you live and what track days you plan on attending, but I am sure there is a fellow NESBA person nearby to help you get off on the right foot.