Just be yourself. This is supposed to be fun and relaxing!
Presumably you have read through the ladies site and have selected a companion whom you know you will get along well with. Ensure you are familiar with her etiquette section as well (though most of it is common sense such as being on time, being clean, being considerate of her discretion and not calling her name over the buzzer system or banging loudly on the door etc.)
Other than just common sense, you really don't need to do anything special to ensure you have a wonderful time. Communication is always key, and if something is not going as well as you had hoped, just politely mention it or make suggestions during your time together. Each new suitor brings fun and excitement, but there is also a learning curve, so it is imperative that you let her know what is working for you and what isn't.
The experience is your fantasy and all about you. As companions we are wanting to ensure you have the most memorable experience possible, but we do need your feedback during a liaison to make sure we are on the right track.