Contract -NSF fees?

[gravy_train]

yes! you need an nsf fee and a blurb about follow up payment (ie you reserve the right to dscontinue that method of payment). i would also add a late payment fee if parents pay by cash or emt ad enforce it.
specify not only the day that payment is due but also the time, otherwise you will get those parents who email you their payment at 11pm on the day it's due.