How do you turn on the light? Because that’s one way to look at writing. You have to turn on the light in your fiction. You have to bring your world and story out of the darkness and into the light.
There’s a lot to the question though. The answer would have to cover all the aspects of craft and the somewhat less definable aspects beyond craft. It’s kind of like saying “how do you write a novel?” There are many many answers for that. You can say one sentence at a time but how much does that help? You can say focus on the characters but…that’s only part of the story. There are so many things you have to do at once without thinking (while thinking a lot) in order to write a novel.
Bradbury says get out of the way. Let your intuition take over. I do think that sometimes you have to do just that. Let yourself be the story, be the characters, and the light will come on. By this I mean see what’s happening through your character’s eyes. Let the light come from that. Move with the character, think with the character, respond to the plot and setting with the character. Create the story from the inside out.