Why this is a mistake: I suppose there are some people who come out of the womb as natural-born writers (but if you really study the truly gifted writers, you will learn that even they spent great amounts of time and energy on learning their craft and art). Then there are the rest of us. We have to learn the craft. While there are many ways to learn the craft, one of the best is often the most overlooked by aspiring writers: learning from those who have mastered
The solution: Have you ever gone into a museum and noticed all those art students seated in front of the classic paintings, sketching them? Writers should be no different. Study the works of better writers. Break their work down and examine the structure. Ask yourself why the author did everything she did. I once picked a week and read the fifteen books that were currently on the New York Times best-seller list, regardless of genre and whether I liked them or not, simply to learn. And I learned a lot. If something is successful, study it, regardless of how you feel about it. That doesn’t mean you have to do what that person is doing, but it does mean you have to understand what that person is doing.
Note that I read current books. While studying the canon of literature is good, classics from the past might not be so applicable to the twenty-first-century world of publishing.
Do this not only with writing, but with any type of art that comes close to your own. As a novel writer, I study movies, their similarities to novels, and their differences from novels. If I were a newspaper reporter, I think it would behoove me to study film journalism.
Read biographies of their lives in order to understand how they approached their art and also how their careers progressed. Also study how they approached the business.