(1) A Basic Outline:
Start with the big plot points. For example, when does your main character enter a new reality or embark upon a journey or quest? That’s the demarcation line between the old story world and the new. If you’re doing a three-act structure, this will be the beginning of Act II. It’s often a great place to start.
You’ll want to go through each Act and list your scenes. You can be as basic or as detailed as you’d like.
(2) The Reverse Outline:
Mix it up! Start at the ending and unwind from there. The kingdom is saved, but not before a final battle in which the hero is injured, but not before he has one last tryst with his true love, etc. Rewind the clock to explore how you can reach the ending.
(3) Milestone Moments:
Maybe a full outline is too intimidating. I tend to fall in this category. What I do instead is focus on the big events that I know must occur for the character to make her way from point A (beginning) to point B (midpoint) to point C (resolution). You might have any number of these moments and it’s okay to start small.
Some writers called this the tentpole approach. These are the story events that, if they were missing, the plot would fall down.
(4) Beat Sheet:
This approach might appeal to you if you enjoy spreadsheets and getting down to the details. It involves charting each beat of the story in every scene. You don’t need to include description or dialogue, just the events and developments.
(5) Draft Zero:
If outlining and beat sheets aren’t your style, try what some refer to as a “vomit draft” (sorry!) With this approach, you’re trying to dump it all out there on the page. It’s not fancy. It might not even make sense. But you’re getting words on the page, and you can fix it later.
There’s no one right way to plan your story. Even if you find a solution that works for you now, your next project might benefit from a fresh approach.