First of and more importantly, you should always be seeing highly reviewed and established ladies to avoid any surprises. Sometimes, the argument is what makes someone a highly reviewed and established person? At least 5 reviews from established reviewers preferably recent reviews, a website, photos and enough information to make your decision making process easier.
In regards on how to contact he lady, remember that you can always ask if she has any reviews and if so on what website. In order to determine the best way to contact her, you will need to read her website, reviews and do research, most information should be readily available. My personal preference is gentlemen who provide as much information for screening as possible so we won't be going back and forth or who simply complete my form and those who do not disclosed anything explicit (you get extra points with me for great spelling and perfect sentence structure), here is an example:
Hi (insert provider name here)
My name is (your name and age) and I am interested on setting up an appointment on (date, time,length, city, incall/outcall request, if outcall location/hotel).
My recent references are:
(insert references here)
My TER handle is (Insert handle here)
Please confirm your availability for the above date and let me know if you require any other information for my verification.
Regards