I started out of course with Hemingway when I learned how to write. Until I realized Hemingway doesn't have a sense of humor. He never has anything funny in his stories.
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 Leonard