A rank in Profession (prostitute)? Rest of the character whatever you want, however you want it?
Because, you know, most prostitutes aren't specially trained or anything. Or even especially beautiful or charismatic or whatever. In fact, most prostitutes are very miserable women who got handed a lot of crap by life, and by men. They don't WANT to prostitute themselves, they're not getting anything out of it except for a little bit of money and a lot of abuse, and it doesn't especially make them good at anything an adventurer could use - except maybe a cynical enough outlook on life that being stabbed in the face by a random Orc's lucky crit at least doesn't come as a surprise.
IF a prostitute is indeed lucky enough to escape that life, and becomes an adventurer, she'd need to have an entire different skillset than cheap come-ons and low self-esteem.