A hidden connection is stronger than an obvious one. - Heraclitus of Ephesus
Connecting with the audience. This is paramount. If the audience isn’t invested with the story, if it doesn’t care about the characters, if it’s not intimately involved, anticipating, reaching conclusions, and adding it up... well, then you’re in trouble, riding a sinking ship.
Understanding your audience is essential. All good writers (reporters, cartoonists, novelists, and the like) craft their work with the audience in mind. Even Shakespeare wrote to an audience - from the poor, illiterate goundlings to the privileged lords and gentlemen of high society - and he used an array of devices to connect and involve that wide audience with his plays.
This is your job as well: to learn and master specific tools of the trade that help to create connections with your audience and make them active participants, not simply static observers. The audience is your customer, and you must write to that customer - Always!
And why? Because even though a screenwriter may not be rewarded with Pulitzers, he can earn comfortable sums of money. There’s nothing wrong with wanting to get paid. But the screenwriter who ignores the audience will struggle to find sellable success. We don’t make movies for one person. We make them for the masses, the many, the mob - sometimes the general universal audience and sometimes a specific one - but in the end, without the audience, there is nothing: no film, no script, no screenwriter.
It's helpful to think of screenwriting as a triangle: the writer, the subject, and the audience. No one goes to see a rom-com to be surprised. The audience has an firm expectation that everything works out in the end. The fun is in the journey to that end. Imagine Shrek or Toy Story without the writers considering both kids and their parents - not the same films. When you write with the audience in mind, you'll find it easier to determine how and when to reveal things, when to cut scenes, where to start a scene and how to get out early.
Remember, making movies is a business and screenwriting is a key part of that business. As a screenwriter, you are selling a story to an audience. They are your everything. You write for them - so they can laugh, cry, hope, and fear. But don’t force-feed; your audience is smart. Never just tell the story. You must show, so your audience gets connected and involved. Let them add up two plus two, because when you do, they love you for it.