Back to "The Essay as a Whole"
E.B. White added this first Principle of Composition in his 1959 revision of Strunk's Elements of Style (1918): Make the paragraph the unit of composition: one paragraph to each topic.
In other words, plan your work. Organize your thoughts. Put them into some order of presentation that will be easy for the reader to follow.
The best way to do this is to make an outline--not a key word or phrase outline, but a sentence outline, in which every word is part of a complete sentence.