Promise only what you are certain you can deliver, then hand over slightly more. It rarely takes much: ten extra minutes on a presentation, or a chart nobody asked for. This lesson is itself the bonus, which is why it arrives with three extra pointers for camp people. My favorite is the one about listing your campers from memory and paying attention to which three names came last.
This is the short version. The full lesson, with the story behind it, is in the book.
Take The Summer Camp MBA with you, or get the field notes by email while you work through the lessons here.