No-shows are the most expensive item in this business because an empty hour cannot be recovered. A reminder the day before, a link to move the appointment rather than a phone call, and a cancellation rule that was known in advance: the rate falls quickly and visibly once all three are in place.
Gift vouchers belong in the system rather than a drawer. Issued, redeemed, balance remaining — tracking them tells you in January how many hours are already paid for and still owed, which is an accounting fact and not a detail.
Around that sit the parts that keep the diary full: an assistant answering the questions that arrive after closing — do you treat this, how long, how much — and scheduled email that goes back to clients who haven't been in for a few months, with their history already on the record.