Here are a few suggestions:
Don't waste the providers time with too many txts. Try to get to your confirmed appt in a few txts.
Be clear (communicate) about what you want out of the appointment, be as specific as possible.
Be respectful. While it is a client/provider relationship; both are humans, have needs and deserve to be respected.
Always use the term "donation for your time only" when asking rates.
Shower just before your appt if you are able, and use breath mints or mouthwash.
Ask permission before doing things which might be considered disrespectful - like spitting, slapping, being verbal etc.
Ask about and respect likes/dislikes and if anything is off limits, for example some ppl don't like nipple play, being tickled, cologne, etc.
Generally, don't wear cologne, avoid deodorant unless you have a BO problem. Nothing worse than someone reeking of bad cologne.
I generally try to provide some info about my stats. This will be controversial to some as there have been active threads on this topic, but my MO is there should be no surprises.
Check in during your appt - How are you doing? Everything OK?