[If you would like this passage as a learning support in Microsoft Word, it’s under that hyperlink.]
“12. Choose a suitable design and hold to it.
A basic structural design underlies every kind of writing. Writers will in part follow this design, in part deviate from it, according to their skills, their needs, and the unexpected events that accompany the act of composition. Writing, to be effective, must follow closely the thoughts of the writer, but not necessarily in the order in which those thoughts occur. This calls for a scheme of procedure. In some cases, the best design is no design, as with a love letter, which is simply an outpouring, or with a casual essay, which is a ramble. But in most cases, planning must be a deliberate prelude to writing. The first principle of composition, therefore, is to foresee or determine the shape of what is to come and pursue that shape.
A sonnet is built on a fourteen-line frame, each line containing five feet. Hence, sonneteers know exactly where they are headed, although they may not know how to get there. Most forms of composition are less clearly defined, more flexible, but all have skeletons to which the writer will bring the flesh and blood. The more clearly the writer perceives the shape, the better are the chances of success.”
Excerpted from: Strunk, William Jr., and E.B. White. The Elements of Style, Fourth Edition. New York: Longman, 2000.