You got many answers from people meaning well. Just keep in mind that some might expect you to conform to an orthodoxy you might not like or even be aware of. I have often thought that there is a lot of cult like adhesion and group think about what you are supposed to do and not to do - this is unrelated to any of the previous replies. It will take more than one or a few sessions to figure out what you are looking for and what you need and you are the only one who can do it.

In my first few years I just went through the motions and it took me a long time to figure this out. Don't be afraid to refuse things you don't like or to stop a session which goes in the wrong direction.

Try to do your homework before a session and find out as much as you can about the mistress you are about to meet. Try to find videos or reviews of her in similar situations to what you expect to do. This is time well spent which can pay dividends.