You've seen the ads and I'm sure you've clicked on a few. The difference between all of these sites is usually the backing database of members. Most of them are fairly new and because of that, you can run into lots of them that have little to no real members, especially women. How can you know if you've found the right ones?
The best thing to look for is if the site has something more than just pictures of women. Are there dating tips? Relationship advice? These kinds of things means that the site owner is looking to do more than just push people to a datng site - they are looking to helpt hem out.
My favorite thing to do is head over to a popular one like Fbook of Sex and do a search in my area. I can't tell you how many times I've seen someone I knew on there and got to read all about the dirty parts of their lives!