"Never include anything the audience can reasonably and easily assume has happened. Never pass on exposition unless the missing fact would cause confusion. You do not keep the audience’s interest by giving it information, but by withholding information, except that which is absolutely necessary for comprehension.
Pace the exposition. Like all else, exposition must have a progressive pattern: therefore, the least important facts come in early, the next more important later, the critical facts last. And what are the critical pieces of exposition? Secrets. The painful truths characters do not want known.”