Rules of storytelling, according to Pixar

Emphasize trying more than success.
Having an initial theme while writing is important but don’t get too attached to it.
Cutting things out is important part of the writing process.
Challenge your characters with their polar opposite.
Come up with your ending before you figure out your middle.
Putting it on paper lets you start fixing it. If it stays in your head, a perfect idea, you’ll never share it with anyone.
Audiences don’t like passive/malleable characters, so give yours opinions.
Imagining what you would do in the place of your character helps you lend credibility to unbelievable situations.
Give the consumers reason to root for the character. Stack the odds against them and make the stakes clear.
Story is testing, not refining.
Coincidences to get characters into trouble are great; coincidences to get them out of it are cheating.
Trying to rewrite a movie you dislike into one you like without messing too much with the structure is a good exercise.
Summarize the essence of your story. If you know that, you can build out from there.