My source for information has been
www.punternet.com which is the best. Use the punternet Field Reports to your advantage. I've done 3 in the past (once since removed due to the retirement of the lady). They are good to assess if you'd find the lady compatible to your desires. There's also an advertisement section on punternet (also called "pnet")
Adultworks can be used as well, but success will be variable; some great, some scams. A simple strategy which worked for me is to determine where your hotel is and then search Adultworks for ladies in that area.
A great website to check out is
www.00-44.com . I've had meetings with 3 of their ladies and it was an excellent service. The ladies aren't knock out "pin-up" beauties, but all are very attractive and intelligent. Most are from England, but those who aren't speak good English.
Note that there are independents, agencies and parlours. Parlours are your traditional location where you selection and retire to a room. Agencies you call and select from those on their website and make arrangements for incall or outcall. Independents will do either incall or outcall. I have met independents and agency ladies.