It’s impossible to be prepared for every eventuality. But…
The first time you do something – perform a recital, say, or do a recording session – you can’t know what to expect, or what common pitfalls are to be avoided. You’re going to have to learn, through a combination of repetition and trust in people who’ve been there before you.
As you get more experienced, then, the requirements are two. First, be ready. Know what’s coming, and be ready to handle as many possible outcomes as you can. Second, reassure. The odds are that there’s someone with less experience than you walking into this experience, and your experience can do much to reassure:
“I’ve got this.”
“In my experience, it’s always a good idea to think about _____”
“Have you considered…?”
“Don’t be nervous…we’ll do this together.”
“I’ve been here before; we’ll get through it!”
Be ready. Reassure. And then enjoy the ride.