Cancellations (Nadège)

I’m part of the (amazing!) Coach Certification Programme and I just looooove coaching. I’ve got several clients that I coach for free to practice. I’ve set up an online scheduling calendar.
However I’ve had several free clients who’ve cancelled at the very last minute. I took advantage of that time to read my curriculum books or Ask Brooke or watch a replay so I didn’t really mind.
But I’m thinking of ways to prevent that when I actually need the money that comes with the session. My online scheduling calendar allows for payments to be made when booking the session and I quite like the commitment that it offers for the client. Are there any other ways to deal with last minute cancellations?
Thank you!