What to put in and what to leave out. How I do it.
1. I decide what fiction I'm writing.
(a.) Short story, novella or novel
(b) I try to decide what genre it is.
2. I find it vital to know the conventions of the genre I choose to write in. Obviously I know I can defy these conventions but how far I can do so depends on how well I know the market and how confident I feel as a writer.
3. Before composing a scene I decide:
(a) Whose viewpoint the scene is from. That will affect what I put in, or leave out. (If my viewpoint character is blind, for example.)
(b) What the function of the scene is - How does it progress the story? What will it reveal of character, plot or both? Is it there as a subplot? Or as a contrasting item?
(c) The mood of the scene.
4. Before I begin to write, I jot down what the emotion of the scene is, plus its purpose. I try to keep that in mind at all times.
5. I try to be relevant - Hemingway's adage about not mentioning the gun on the wall unless someone is going to use it. I like to indulge in the telling detail. I know that I should control the description, not vice versa. Sometimes I write in a rush - I get the scene down and then shape.
6. Later, I revise!