Best place to start are the main agencies that specialize in PS providers. Trystagency, PC, AIA. There are also a number of assistants who have their own lists, you can probably find some of them by doing a search of this foru,

Lke most of the real good stuff here you need to be a VIP member.  Then the Provider Search form will let you select all sorts of characteristics.  There's a Porn Star cehcbox

For advertisements go to the buzz boards. TER changed the category name a year or two ago presumably so it's not as overt advertising.

http://www.theeroticreview.com/discussion-boards/porn-star-buzz-109

Otherwise look at Eros, Tryst, Twitter, or the porn star escort agencies. Be careful of scammers.

I always use Tryst and Eros.  I toyed with the idea of registering on Alluring something Arrangements.   I can't remember the name now.  Damn getting old sucks!