Tip #4: Scripts that sell speak to universal subjects in a distinctive voice.
One knowledgeable answer to the question, "What do the studios want?" is: The same but different.
They want yet another comic book super-hero franchise installment, but they want it with a new spin - say, featuring a darker-than-dark villain whose spooky nihilism calls the hero's very existence into question (see: The Dark Knight). They want yet another comedy about an unwanted pregnancy, but they want it from a new angle - say, from a contemporary teen's arch, blackly comedic POV (see: Juno), or from the POV of an unlikely boy-man slacker-shlub who can't believe he even got to sleep with a hottie, let alone got her Knocked Up.
It's for this reason that, should the movie live up to its effective trailer, this Christmas's Sherlock Holmes is going to be a gazillion-bucks-making franchise-starter. What could be more old hat than Holmes? Right, but we haven't seen this Holmes before - muscular and action star-like, with the winking wit of Robert Downey Jr. in the role and an anything-but-stodgy Jude Law in the place of his traditionally fat and nerdly sidekick, Watson. The trailer makes it look like Lethal Weapon in hip Victorian drag.