What is the etiquette on tipping?  Do most people tip?  and if so how much? Do you wait until after to see if you enjoyed yourself and want to see them again and then add it to the envelope?  Not sure 'cause it sounds like you should never discuss the donation or envelope during a session.

Just type "tipping" into the search feature and grab a bowl of popcorn, you'll be there a while.

Executive summary:

It's up to you.  Some do, some don't.

If you do, then yes, after the service is best.  You can palm the cash from your pants pocket just before the parting hug and kiss and transfer it to her hand as yours hand part.  (That's my favorite method.)

I'm tipped on numerous occasions, and every time i am, it's always such a nice feeling because it tells me that my Gentleman totally enjoyed himself, but i NEVER expect it, nor do i ever hint about it, it's not my style, if a Hobbyist wants to tip it's just a really nice thing to do.
If you want to tip on occasion, bring her donation and maybe something extra, what that extra could be is entirely up to you, $25 $50 $100 is up to you!
Jay

but I do bring gifts, candles and VS gift card.  Have not had them refused yet.....duh

Swim

to my special friend. Tipping is nice, but if you know her better, why not do something special.  And of course re booking is the ultimate thank you to most of the ladies.

says so much more than giving her a gift.