William Strunk, Jr.

“ Make definite assertions. Avoid tame, colorless, hesitating, non-committal language. ”

“ An exception may be made of sentences of transition, indicating the relation between the parts of an exposition or argument.
In dialogue, each speech, even if only a single word, is a paragraph by itself; that is, a new paragraph begins with each change of speaker. The application of this rule, when dialogue and narrative are combined, is best learned from examples in well-printed works of fiction.
10. As a rule, begin each paragraph with a topic sentence; end it in conformity with the beginning. Again, the object is to aid the reader. ”

“ In notebooks, in newspapers, in handbooks of literature, summaries of one kind or another may be indispensable, and for children in primary schools it is a useful exercise to retell a story in their own words. But in the criticism or interpretation of literature the writer should be careful to avoid dropping into summary. ”

“ If the writer finds that he has written a series of sentences of the type described, he should recast enough of them to remove the monotony, replacing them by simple sentences, by sentences of two clauses joined by a semicolon, by periodic sentences of two clauses, by sentences, loose or periodic, of three clauses—whichever best represent the real relations of the thought. ”

“ All three examples show the weakness inherent in the word not. Consciously or unconsciously, the reader is dissatisfied with being told only what is not; he wishes to be told what is. Hence, as a rule, it is better to express a negative in positive form. ”

“ More commonly the opening sentence simply indicates by its subject with what the paragraph is to be principally concerned.
The brief paragraphs of animated narrative, however, are often without even this semblance of a topic sentence. The break between them serves the purpose of a rhetorical pause, throwing into prominence some detail of the action.
11. Use the active voice. The active voice is usually more direct and vigorous than the passive:
This is much better than
The latter sentence is less direct, less bold, and less concise. ”