There are already separate laws dealing with trafficking and the other crime related reasons that people drag up when defending the prohibition on prostitutes. Most of the "crime" that people bring up when defending the anti-prostitution laws, the physical abuse, the trafficking, drugs, etc., are in fact PROTECTED by the laws against prostitution.
Think about it, why doesn't a woman who has just been beaten by her pimp go to the police? Because she will get arrested for being a prostitute and the pimp will probably get a lighter sentence than she will.
If prostitution was legal these "Victims", that everyone seems so concerned with protecting that we put them in jail, would be able to go to the police and press charges, or get restraining orders, or even just try to get help without fear of being arrested for trying to take care of herself and her family.
How is renting your body for sex any different from renting your skills as an accountant, programmer or ditch digger to a company/individual in exchange for money?
And before you bring up STIs and "street walkers", consider these ideas;
Require a permit, renewed monthly, that requires a clear STI screening result from a clinic. (funny that one of the complaints I hear about hookers is that they leave used condoms laying all over the place, sounds like they are better at practicing safe sex than most people.)
Most of the hookers you see on the street would move inside where it is safer, if they could just advertise in the paper or on sites like craigslist.