Hi Kat
People have mixed views on it but i get quite a lot of clients from advertising on Vivastreet,its free to put an ad on as well. Also i find Adultwork gets me quite a lot of clients,also if you have a private gallery you can make money from that alone via the credits system they have there.
I think no matter where you advertise you will get your tws and your genuine clients,its just a case of sifting through them.
xxxx