Stuff I learned over time:
If you have any health problems that she might need to watch for, good idea to let her know. For example, I have Cystic Fibrosis, so sometimes I have to be let up so I can cough up any gunk in my lungs . So the pro dommes I play with know to keepsome tissues and a trashcan nearby just in case.
Also, if some technique or tickling tool hurts and you find you don't like it, let her know. I don't care for the metal pinwheels...they poke more than they tickle, so they're not used on me anymore. And the Sonicare brush HURTS one spot on me, so I ask them not to use it there.
Same with restraints. If they're hurting or a limb is going numb or something, let her know so she can adjust the restraints.
Make sure you arrive on time...don't want to waste a minute of the session, right? I try to arrive at least a couple of minutes ahead, and just walk around the area till it's time to let her know I've arrived. Might be more difficult for people who use public transit...sometimes buses or trains can be delayed.
Speaking of delays - if you know you'll arrive a bit later than planned, and have the domme's number, it can be a good idea to send a text or call (not while driving, of course! )
Might not want to eat too close to the session time - I can't imagine throwing up during an intense tickling would be any fun. Probably want to make sure you pee before starting the session , too.
Hmm..I'm sure there's stuff I'm forgetting that I'll remember later. Most important(at least in my opinion) , both of you have a great time!