I just read an article about Stephen King's new book, The Institute. The person who wrote the article admires King's novels but in this one he got to chapter 7 and there was still no story.
The Amazon blurb for the novel reads, "In the middle of the night, in a house on a quiet street in suburban Minneapolis, intruders silently murder Luke Ellis’s parents and load him into a black SUV."
That's intriguing, but even by chapter 7 there was no hint of that story.
Of course, King has millions of followers who are happy to let him take his time to get the story going, but the rest of us will do better to follow the advice to open your novel or screenplay with something intriguing going on that draws us in and has a strong connection to where the story is going.
THE PROBLEM WITH NORMAL
Usually, the first chapters or script pages are about the normal life of the protagonist, before the inciting incident that draws them into the main story. That allows us to identify with them and gives us a sense of their strengths and weaknesses. For instance, in a story about a teacher who is falsely accused of having an inappropriate relationship with a student, the first act of a screenplay or the first chapters of a novel would give us a sense of the life that's about to be destroyed. The problem, of course, is that normal life typically isn't very compelling.
Foreshadowing is giving a clue about what's going to be happening later. In our example story, we might have the teacher discipline several students for a prank. One of them comments to the friend who leads their little clique that he's surprised the friend isn't more upset about it. That student says, "That's OK. She won't be teaching our class--or any class--for much longer." OK, maybe a little heavy-handed, but it makes us wonder what he has in mind and we know it's not going to be good. That keeps us interested and buys the writer some time to get more into the life of the protagonist.
FORESHADOW WITH A METAPHOR
If you can't foreshadow with an incident directly tied to the story, sometimes you can foreshadow with an incident that serves as a metaphor. For instance, during the teacher's happy birthday party there's a scream as one of the guests spots a rat running through the kitchen. Even though rats will not be playing a role in the rest of the story, it gives a hint that in the midst of this happy norm, there's a dark element that will disrupt her life.
This is especially useful if you have a story in which the tone changes drastically as the story goes on. It helps to prepare the reader or viewer on a subconscious level for what's to come.
USING BOOKENDS
You can open at the end of the story if it's exciting or intriguing, flash back to the start, build to the same ending moment with which you began. For instance, you might start a script with your protagonist on the gallows. As the noose is placed around his neck, he turns to the camera and says, "It all started so innocently..." Then you flash back to how it started and continue until we're at the moment with which you started. Then, either he dies, or he manages to get out of being hanged and is available for a sequel.
Another example is Titanic, in which we see old Rose at the start and end, but the core story belongs to young Rose.
OPENINGS TO AVOID
One opening to avoid that I've seen sometimes in novels and short stories is something like, "Little did Posie know that in a mere few days her life would change forever." Clunk!
A dream, especially a nightmare, as an opening tends to feel like a cheat, especially if we don't know it's a dream.
Prologues can work but tend not to be popular with publishers. Sometimes the prologue is a moment in the heart of the action, a preview of what's to come, and then the novel starts back at the beginning. Or they might show, for instance, a trio of witches brewing up a curse that will come into play later in the story.
IF YOU CAN'T THINK OF A WAY TO FORESHADOW
If you can't think of a good idea for foreshadowing as you write the first pages, don't worry. It can be easier to come up with that idea after you've gotten farther into the story or even completed the first draft. Often, I'll just write the first act without it and then go back and add it.
And once you get to be as popular as Stephen King, you won't have to worry about it!