- You show up to play a lesson and no one is there: Immediately call the student to remind them to contact you next time that happens.
If it occurs a second time, call the student again, and mention it to their teacher. If it happens yet a third time, either ask the teacher to directly get in touch with you next time, or talk to someone at a higher rank than you.
- Your students want to rehearse with you when their lesson is canceled: make the students aware that if you do rehearse with them in place of their lesson, you won't attend the make up lesson.
If the teacher asks you later to still do a make up, you may do so, but in place of that week's rehearsal.
- Your student scheduled a jury without telling you: Take the bull by the horn, and schedule all of the juries yourself. As soon as the sign up sheet is posted, call every single one of your students to arrange their jury time.
The advantage of doing that is that you can actually put your students back to back, instead of waiting around in between juries.
When you can't get a hold of someone, sign up for a jury time anyways. Chances are that time will work for them, and if it doesn't, you can most likely swap it with another one of your student's time.
If swapping doesn't work, you can be sure that your student will know to keep you involved in the process.
- You're not getting paid: Before you play with someone, agree with them in writing on a payment method and on a schedule for it. To be on the safe side, ask to be paid before your service is done, such as at the dress rehearsal, or right before a jury.
Many schools have a policy which states that should a student not pay their accompanist, they will receive an incomplete for their lessons, or they won't graduate. Print up that policy and post it outside your studio.
When a problem ensues, you can find leverage by telling your student that if they don't pay you within a certain frame time, you will let the university policy take care of it. Students' teachers are usually of great help in such situations, so involve them when needed.
Picture from http://crossfitscottsdale.com/homeblog/2011/02/i-jerks/baby-lifting-weights/