Good for you for wanting to help. You've received some great advice and I echo the don't go it alone and do some research to find out exactly what you are getting yourself into before you do anything.
In my extremely limited experience or that of my friends' in working with prostitutes there are a few things I can say; first off no little girl wakes up one morning thinking, I want to be a prostitute when i grow up. There is always another factor, usually financial, that keeps them in prostitution. It could be a pimp, some sort of bonded labor or debt payment arrangement, or the family needs money and this is a way to make money for my family. I'm living overseas now and recently heard a story that for one poor girl it was the promise of work for a $20 internet bill at the internet cafe that she became vulnerable to the promise of employment offered her by traffickers. The human trafficking thing is very real and yes usually starts with a promise of employment. Get someone in a foreign country where they have no right to be, don't know their way around or speak the language and they are very vulnerable. This sign hanging in a corner grocery store in Asia was my brush with it a few years ago:
I also remember hearing a few years ago that many organized crime groups were turning to human trafficking because it was more profitable and less risky than dealing in weapons or illegal drugs.
One other thing to be aware of is that in order to keep themselves together a lot of prostitutes have to develop a very cold and proud demeanor. They may well give the impression that they are proud of the fact that they are working, providing for their families, or anything else they tell themselves to make life bearable, and they can't afford to accept your sympathy and pity. Also even if you manage to help a few get out, they will often head back to rescue someone they know and get ensnared again themselves.
The flip side of all this is that the smallest act of kindness or generosity can mean the world to someone in this situation. I had a friend (female) working in prostitute ministry who got valentine's flowers for the girls and they talked about that for months. So my best recommendations to you are to network with others who are fighting human trafficking and prostitution (an internet search should do the trick) and if you feel the need to do something immediate find someone to work with you (do not face a group of prostitutes who are under pressure to seduce you on your own) and maybe just start giving small non-intrusive gifts to remind these ladies that they are valuable.
Hope this helps. God bless you as you seek to bring his light into such a dark place.