Get yourself a master class in writing from some of the best living writers. The Guardian has been collecting ten writing tips each from some amazing wordsmiths. Among my favorites: Jonathan Franzen, “The reader is a friend, not an adversary or a spectator.” Elmore Leonard, “If it sounds like writing, I rewrite it.” Neil Gaiman: “Remember: when people tell you something’s wrong or doesn’t work for them, they are almost always right. When they tell you exactly what they think is wrong and how to fix it, they are almost always wrong.” And Michael Moorcock: “I always advise people who want to write a fantasy or science fiction or romance to stop reading everything in those genres and start reading everything else from [John] Bunyan to [A.S.] Byatt.” Many more illuminating rules at both links. [Guardian and Guardian]
I can't speak as a writer. But as a reader, I do think it's in my best interests to be broadly read: both fiction and non-fiction, and amongst fiction, not just SF but also historical novels, mysteries, mainstream, what have you. The more widely read you are, the better a reader you are, IMO.
And, if my experience is any indication, the pickier you will become about what you read. But that may just be old age talking: