Cal Newport on King:
King was careful to always aim above, but just barely above, his current skill level. His first published story was in a fanzine — the 1960′s version of a blog. He moved from fanzines to second-tier mens magazines like Cavalier andDude. After he cracked that market he moved on to top-tier mens magazines and top-tier fantasy and science fiction publications. Only once he could consistently hit those targets did he succeed in selling his first novel to Doubleday.
Good stuff about honest feedback and how to stretch yourself. This is exactly what I hope to do for my writing students.