Cash is King and you should work on getting YOUR best Bang for the Buck.
Most GFE ladies here enjoy seeing hobbyists who are respectful and courteous; these ladies will often lend a helping hand or whatever is needed to make sure you enjoy your session. To paraphrase what GJ said above, relax with the lady and let nature take its course.
Check reviews and posts to find the right GFE provider who will provide the services you desire; also attend some of the local socials to first meet providers who you may wish to later meet BCD.
As an old and not so skinny hobbyist, I have found most ladies appreciate Hobbyists who:
1. Show up on time,
2. Leave on time,
3. Are clean and fresh or take a shower upon arrival,
4. Have and present the proper donation up front,
5. Treat the lady with courtesy and kindness,
6. Respect the ladies boundaries, and most importantly,
7. Communicate any special needs or desires ahead of time.
That said, communicate with your provider and most sessions will be enjoyable...