You may have a list of ideas that need to be worked out, but one of them is likely to be your favorite. Begin with that narrative. Many authors produce their greatest work when they are emotionally immersed in their characters and narrative structures.
Fiction writers need to think like editors and publishers. In other words, approach your story with a marketing sensibility as well as a creative one to sell your book. There are also many sub-categories you can choose from:
Writers are well-versed in the framework most stories follow, from exposition and rising action through to the climaxand falling action.
Your main characters should have a backstory that informs their actions, motivations, and goals.
Identify what will be your starting point, your inciting incident, your rising action, your turning points, your climax, your falling action, and your final resolution.
As you write, you need to make sure you aren’t leaving a trail of dangling narrative threads.