Nothing complicated. Come as you are.
If the session is online, it helps to be somewhere quiet where you won’t be interrupted. A comfortable chair and a pair of earphones are all you need. You don’t need to be in a particular headspace or arrive feeling calm. Most people don’t. Some arrive feeling anxious, sceptical or unsure whether any of this will work. That’s completely fine. None of that affects the process. Some clients have even done sessions in the quiet of their car, away from their kids!
The one thing that does make a difference is being genuinely open to change. Not certain it will work. Not even particularly optimistic. Just willing to try. If you have that, everything else takes care of itself.