Relax
Enjoy it.
Look out of the window rather than inside at the instruments, unless specifically told to look at the instruments.
Don't try to analyse what you're doing, especially verbally, too much in the air. File that stuff away for the debrief with your instructor after landing.
And remember, even learning to fly is fun, and your instructor is there to keep it both safe and fun - so trust them and just enjoy the whole process.
Once you're a little further down the way, always take the time to do any preparation that your instructor asks of you.
G