In one of her answers, she touches on something that I think may be the single most important thing that an author needs to know to become a better writer:
What is the biggest mistake you think writers today typically make in the genres you represent?
Not reading widely enough. Not just in their own genre, but out of it as well; and non-fiction too. I know in this fast-paced world, one never feels they have enough time. I have to work at it to find time to read more than just submissions myself. But I think it’s important for writers to also participate in the community as readers.