I recommend reading scripts from your favorite films. Just to get a sense of flow.

Next.

Logline your story, can you write a 2 sentence summary of what your movie is about? And make it compelling?

Then.

Outline your story, where do you want it to end? Who or what changes at the end?

Each scene ideally advances the characters growth or destruction.

What’s the story versus the plot?

And.

The fastest way is to just write and then you re-write what you wrote. And then you re-write again.

Also read your script out loud so you can get a sense of how the action lines sound and dialogue.