Do you pay the house fee and then wait to see what she asks first or do you tip up front and trust that she knows the deal?
I usually pay the house fee once in the room.
If the provider looks promising and attractive , I then place the tip on the table and make sure she sees it. Never negotiate or you have broken the law.
If experience is top shelf, I will at times leave an additional tip. Found it is a great motivator for future trips. Even if you see a different provider next time, the word has been spread to others.