It may sound like a lot more money, but when I was on eros I got so many calls and offers that I could pick and choose the men. I used Eros Chicago VIP, and I paid more to be listed as VIP, but I was able to pull between 5 and 6 hundred an hour (I didn't have my price listed) and got enough regulars that I was able to bring my page down completely after 2 months.
Hope this helps!
Other than that, Craigslist is really popular here, I don't know if it is active in the UK. It's free! I would post in erotic service, like all the other girls, but I also put a more personalized ad in the adult service section; I entitled it something like True GFE For One Gentleman.
Other than that, contact some of the girls who are doing well and say you have a client interested in a double ( you should be able to find at least one guy willing to spring for 2 girls if you are getting 3 calls a week!) . Let them work with you and recieve 1/2 the money, then offer your services the same way. Let them know that you think doubles are easy money and if their clients are willing you will make the transaction as easy and painless as possible.
If you have a client you are incompatable with, that you aren't interested in seeing anymore, set him up with one of the girls you are hoping to get work from. She may appreciate the client and be more willing to send her cast offs your way.
It would be really wierd to call a client and try to get more business out of them for yourself, but completely acceptable, and sexy, to call on behalf of another girl. Guys love this, it makes them feel like they have entered into a next level of "the escort world"..
Everybody benefits.
Also, be sure that your clients become regulars. Go the extra mile in the beginning. Be ready well before they get there (I'm always running late, the quickest way to put off a client!), make sure the ambience of your place is as lovely as possible, do kegels to make sure your tight down there ( I used a kegelmaster and highly recommend it to working girls), get really in to the massage so it doesn't just feel like a timewaste ( I often do this after sex), ask the client on the phone if there is anything special you could wear for them, be fantastically groomed.
Also, text your clients! Use all good excuses to keep in touch. Every holiday or serious event is an excuse to send a text your clients. Keep the tone sexy and friendly. You will be surprised how often this turns into a booking. I also send out texts like.. " I just got back in town, miss you.. ; ) " ... on a Monday morning. It doesn't matter that I've been chillin at the house all weekend. The effect is still that they are more interested.
Hope this helps..
Best of luck!