Just to echo what Barbie said, don't tell clients you're new. If they say "I haven't seen you advertise before" just say you've only recently moved to the area, or that you've only recently become independent. There are some dickheads out there who deliberately target new escorts and try to push boundaries.
Also, you're not taking a vow of service here. If you see a client and you realise sex work isn't for you, you can stop. It really isn't for everyone. Yes the money is great but don't do something that you hate, because it will impact your health.
Go to your first booking with an open mind, if it's awful then you never have to do it again. If it's okay then, wahey!