I'd be interested to hear about how different teachers ask for and accept payment.
I'm a knitting teacher and I started off about 5 years ago not asking for any money in advance, just cash on the day. It took about 6 months of endless no-shows before I started asking for a 50% deposit. Then on the advice of students, I made this 100% deposit with a cancellation policy (see below).
But there are still times that people book and need endless chasing for payment (these are the one's that want to pay last minute and they often cancel last minute).