The way I handle my sessions is one flat rate. The only thing I ask for an additional fee is:
Greek, edging, fetishes and duo sessions.
I do however expect either a tip or something off my wish list. It is not required obviously but quite appreciated. If you visit me and find that I am. clean, on time and have done a great job it’s only fair. If you do it that way the tip would come after the session.
However, you won’t get any of the extras as the session will be over when you give it to me. I would like to suggest that you tip at the beginning of the session. That way I know-how extra grateful I should be.
Either way works of course and it is totally up to you!