1. Don't teach what is not on the sylabus i.e. don't treach 60 deg bank turns when only 45 deg is on the sylabus. Get them back after the PPL for more "advanced" stuff if they want.
2. Have a system in place for students to report "differences" i.e. where instructors ask for things to be done differently. These differences are then discussed and an agreed method is used.
3. If one does not ask for feedback one will not get it. Break the PPL or whatever course into stages and ensure that the student provides feedback at the end of each part.
There is 3 for starters.
Regards,
DFC