Books on writing are even more common than first-year Greek grammars. (I should probably revise that sentence.)
Here are six that I’ve found especially useful. I’d suggest reading them in this order.
1. William Strunk Jr. The Elements of Style. Wth revisions, an introduction, and a chapter on writing by E. B. White. 4th ed. Boston: Allyn and Bacon, 2000. 105 pp.