Most of the stories he published look pretty crude now, but they were stories. Concise, clearly written, about people solving problems. […] The hero had to be sympathetic, pitted against ugly evil. The conflict had to keep moving, rising steadily from a quick beginning to an exciting climax and then a triumphant resolution brought about by the hero himself.
Though such rules aren’t enough to make a story great, they do reflect fundamentals the writer has to master before he can ignore them. There are ways to win and hold interest. If the reader isn’t interested, early and firmly, all else is lost.
Source: Williamson, Jack. Wonder’s Child: My Life in Science Fiction. New York, N.Y.: Bluejay Books, 1984.