Very Little FluffYes, I worked from a script, so in a book the author would have to go into more detail about the visuals on screen (the world building) as well as the main characters internal thoughts. But if you strip all that out of your book, will it stand on its own merits? Remember that I was posting on twitter, so I was limited in character count. I didn't post any of the "fluff" or any lines that, by themselves, didn't add much or weren't an interesting tweet. What I found was there are very few lines from the script that needed skipping. Very little fluff.
Lesson: Make every single word count and skip the boring bits and fluff for the sake of word count. Ask yourself, if I take this out does it make a difference?
Quick DialogAlmost all of the dialogue is quick. Each character saying one or two lines at the most. Very few long speeches or monologues. Think about how many one-liners from the movie are immediately recognizable.
Lesson: Short, rapid dialogue is more memorable and keeps the pace going.
Optimism Despite AdversityThe characters are charmingly upbeat despite finding themselves in serious situations. Think about things like what Westley says when they're in the fire swamp. "I'm not saying I'd build a summer house here, but the trees are actually quite lovely." I find this makes the characters more endearing and keeps my interest. Picture the story as an uber-serious drama. I'd be bored in a heartbeat.
Lesson: You can have drama and adventure but not get mired in the melodrama.
Go With the UnexpectedThe characters rarely do what you'd expect. I mean, why would someone train themselves to ingest poison, or give the guy they're about to fight a rest since he just climbed a cliff?
Lesson: It's okay if your characters do the unexpected as long as they are true to who THEY are.
Surprise Yourself (Inconceivable is Still Possible)Westley is killed half way through the book (the 2nd time). That's what, as an author, I'd call a corner. A spot where you have to ask yourself how you're going to write yourself out of it. We think of corners as bad, as something to avoid, right? But I've read the author of the book himself didn't realize that he was about to kill his main character. But Westley being only mostly dead which is a fantastic fix. We wouldn't have that if the author didn't do something inconceivable first.
Lesson: As a writer, you should even surprise yourself with what your characters do and what happens to them. DO paint yourself into a corner.
A Little Mystery is a Good ThingI find it funny when readers or beta readers want all the mysterious questions answered in the first few pages of the book. Where's the fun in that? In The Princess Bride, many mysteries are left unanswered for a long time.
Lesson: Writers, you have permission to torture your readers with mysteries if it makes the story more compelling. Just don't make it confusing.
Perfect is BoringThe characters in The Princess Bride are not perfect people. Westley leaves his love thinking he's dead for five years, and has probably done some bad stuff as a pirate. Buttercup is marrying a man she doesn't love. Inigo is a drunk.
Lesson: Give your characters flaws that they have to overcome or which drive the plot in a way that is true to the character and true to the story.
In the same vein as what I've learned from my daily inspection, a line at a time, of The Princess Bride script, I ran across this fabulous article. It's an EW article with 30 life lessons from the movie. Enjoy!