how to please, tip or not to tip
Well it comes down to first how well you felt the session went. Even further it may come down to how well you felt you clicked with the lady on a more personal level.
I've seen sp's that gave mind blowing sessions, ie technique; but still seemed very cold and detached.
Your both human beings in the end so maybe think in terms of how you enjoy being treated by someone trying to show you they appreciated something you did for them. (don't know if that made sense?)
Some simple expression that says "I had a really great time, or I'm really glad I got the chance to meet you....or GOD I CAN'T EVEN WALK!"
I've tipped before, amounts may vary, but I do like the personal touch. Flowers, wine, something small, it doesn't have to cost an arm it's the fact that I felt the person deserved my putting the thought into it.
Let the lady feel like a lady and not just a flavor of the day.
Hell even in my own job I enjoy being recognized when I've gone an extra mile, or even if someone just has the time to say thanks.