There are two things that will probably help you more than any response you'll get here. The search function for this PS board and the search function for reviews.  

No matter what though, you'll still need to go through a screening process to make anything happen. For most agencies you will probably need to have references of (non-porn) girls you've already seen. Some of them might even want to screen your girlfriend too.

Yeah!  Your going to both need references to even get started or a boat load of cash.  These ladies just don't show up at your door.