I just finished working with a personal trainer, so I might be able to answer some of your questions.

Now, I got her through my gym; she is their employee. So I didn't pay her directly. I didn't tip her either. However, we did meet once a week, on a schedule that worked well for both of us.

It was a package deal: 4 sessions, once a week. She was great!

Good luck with getting more answers...