What Cheflayne said ^^
Communicate clearly your expectations to your staff and don't accept less. They will test you.
Discipline in private, never in front of their peers.
Teach, if they don't already know, about waste, food cost, and how it relates to them -- less waste means more business profit -- they'll have a job to continue to go to, holiday bonus, etc
Teach your sous or another capable cook the budgetary and ordering side so that you can have a vacation or get...