I have been in this lifestyle for quite some time and you just turned 18 and are brand new some brutal Mistress could take advantage of you. In my experience the dommes are way worse than the masters. This is my suggestion you can take it or leave it:
Build a relationship with your dominant built on trust, honesty and respect
Don't get into shallow relationships with someone who is just going to bark out orders and make you beat yourself.
Do not ever show your face until you have gotten to know someone for a while if they demand it then too bad a good dominant will wait.
Many people blackmail subs by their face pictures and expose them to the world.
Last of all never pay a penny to a dom.