These are rules I've picked up along the way to help me remain invisible when I'm writing a book, to help me show rather than tell what's taking place in the story.
Elmore LeonardNever use an adverb to modify the verb 'said' . . . he admonished gravely. To use an adverb this way (or almost any way) is a mortal sin. The writer is now exposing himself in earnest, using a word that distracts and can interrupt the rhythm of the exchange.
Elmore LeonardI've quit writing screenplay [adaptations]. It's too much work. I don't look at writing a novel as work, because I only have to please myself. I have a good time sitting here by myself, thinking up situations and characters, getting them to talk - it's so satisfying. But screenwriting's different. You might think you're writing for yourself, but there are too many other people to please.
Elmore Leonard