suggestions on how to play dom/sub in a session

I may be having a session in which I play the dom and she plays the sub.
I know what i would like to do and how it fits into my fantasies, but from the submissive provider's point of view, what are some things you like when being submissive?
I won't be discussing activities with her, as it is intended to be spontaneous and not planned.
She already knows it will be dom/sub, but doesn't know details of what will happen.
It won't be anything painful but there will be spanking involved.
Dirty talk, humiliation, etc.
Probably no bondage this time, but maybe in the future.
I have seen this provider many times over the last 10 years.

Any helpful input is appreciated.

I personally would not participate in a dom/sub session where there would be no discussion of what would happen first. Communication and consent are extremely important and if you don't know what both your limits are, haven't established safe words or signals, don't know the other person's experience level, don't know their mood that day, don't know if they're experiencing pain or discomfort somewhere, etc, etc there are so many things that could make it a bad session. I know you said you know each other but that is the input I have on the type of session you're describing. I also know you said it's to keep it spontaneous but you can discuss activities and details while keeping some things unplanned (like when it will happen or adding an element like a blindfold during play so acts can be surprising) and no amount of spontaneity seems worth giving up the communication part to me. But I hope if that session happened it was fun for both of you. Stay safe