I'm not the first to notice that you can apply Kurt Vonnegut's Eight Rules for Writing to improvisation. But in case you've never seen these or missed the connection, I thought I'd post them here. All you have to do is change some of the words (which I did below with brackets) to make them fit more perfectly for our world.
- Use the time of a total stranger [audience member] in such a way that he or she will not feel the time was wasted.
- Give the reader [audience member] at least one character he or she can root for.
- Every character should want something, even if it is only a glass of water.
- Every sentence [spoken or physical action] must do one of two things — reveal character or advance the action.
- Start as close to the end as possible.
- Be a sadist. Now matter how sweet and innocent your leading characters, make awful things happen to them — in order that the reader [audience] may see what they are made of.
- Write [perform] to please just one person. If you open a window and make love to the world, so to speak, your story will get pneumonia.
- Give your readers [audience members] as much information as possible as soon as possible. To heck with suspense. Readers [audience members] should have such complete understanding of what is going on, where and why, that they could finish the story themselves, should cockroaches eat the last few pages.