Bananamuffin has it in one, couldnt agree with her more.
Personally though, I do tend to take more of the SD approach, rather than work as a proper escort. I did so a few years ago, by myself, and experienced loads of timewasters.
However, as people have previously said on here, there are a few genuine guys on SD sites, though sadly, most are just looking for cheap escorts. I have met loads of timewasters, although I have stuck to my guns. I say that if we get on on the first date, and he wants to take it further, I expect a generous cash allowance. I dont allow bareback, or anything else I am not comfortable with, no matter what crap they may throw at me (e.g. oh, but I have had the snip, I hate condoms)... so? my health is more important thanks!
I think with these sites, you need to be persistant. It is never a good idea to say you are an escort, as chances are, you will just get loads of abuse and banned from the site.
The way to approach them? Just be friendly, and then find out what they are looking for. State what you are looking for as well, and see if he is happy with that. From my own experience, I would say be prepared for alot of timewasters (the amount of people who just want wank material sent is ridiculous), and alot of abuse. I have been called some very horrid names and had to develop a very thick skin.
I have managed to get a few regulars as a result though who are kind and generous. It's worth it I think if you stick at it, but it is a little bit time consuming!