Books on Improving Your Writing
If you write poorly you should consult writing textbooks for more detailed advice. Two good ones are:
McCloskey, Donald. 1987. The Writing of Economics. New York: Macmillan.
Strunk, William, Jr. and White, E.B. 1979. The Elements of Style, 3rd ed. New York: MacMillan.
If you want to persuade the reader, then follow McCloskey's advice: write so you cannot possibly be misunderstood. That means edit what you write. Even great writers edit their stuff. Ernest Hemingway rewrote the last page of Farewell to Arms 60 (yes, sixty) times. And that was before PCs made editing a breeze. Moral of the story: The first time is not always the best.