Have a mission statement and vision that clearly states the purpose of the organization is to support the program by supporting the students and the director(s). I am 100% sure you will be referencing this in the future.
Make sure that the financial records are audited by an independent third party (CPA)
every year. Directors do not handle booster money in any way.
One last piece of advice: The most supportive parents that volunteer enormous amounts of time to the program can turn on you. My experience is that most will expect something special in some form for their child, and when that happens it usually ends up in an unpleasant situation.