I understand your concerns, you want to be well received not just tolerated by a provider. I have to agree with the other responses, a good provider doesn't care about your appearance. Being on time, a person of your word, being polite/respectful are the only things I care about.
I'm very much myself in sessions so the other person feels comfortable with themselves too, most providers behave this way. Don't worry about that stuff, just be polite and respectful and you'll have a great time.