Freely printed from: https://learn.nimja.com/basics/subject_agency
In many ways, the hypnotist is the driver during a session. In control of the flow and direction.
As such, they also have the responsibility to monitor their well-being and inform or adjust the subject.
A subject, even in a very deep trance, can still (unconsciously) think or decide for themselves. However, not everyone is aware of this.
It's very nice to inform a subject that they (for example) can:
To aid in this, it might help to inform them that telling the hypnotist of something that need to change will make the session even better. As you can't read their mind.
It's also important to compliment or otherwise positively receive any feedback, so they are encouraged to keep letting you know of anything that could make the session even more awesome.
Paying attention to the position, expression and behavior of a subject during trance will give you a lot of non-verbal feedback on their current state. Are they happy? Do they need to adjust? Did your last suggestion cause a smile or a frown?
The more feedback you have, the better you can make the trance and the better you get at it. Which improves everything for everyone.