I've always taken a shower before meeting. Naturally it wouldn't be much fun to go down on a sweaty, smelly lady or vice versa. Being clean is one of the most thongs stressed by a provider when asked this question.
As far as tipping goes. There were a couple of providers that I did this with on a regular basis and they started expecting such as basically making it part of the donation. And getting an attitude if not getting it. Unfortunately it's been my experience that tipping makes no difference. Now I know that isn't the case with all providers but with me those that treated me that way kind of ruined it for the ones I would have tipped. I've even had one tell me "you know I think I deserve a tip". This was for a session that was no different then the rest or even more time than was agreed on. That got under my skin a little.
I'm thankful to the ladies here on eccie that have always showed me a good time