Effective Writing

It is a good exercise to try for once in a way to express any opinion one holds in words of one syllable. If you say "The social utility of the indeterminate sentence is recognized by all criminologists as a part of our sociological evolution towards a more humane and scientific view of punishment," you can go on talking like that for hours with hardly a movement of the gray matter inside your skull. But if you begin "I wish Jones to go to gaol and Brown to say when Jones shall come out," you will discover, with a thrill of horror, that you are obliged to think. The long words are not the hard words, it is the short words that are hard. There is much more metaphysical subtlety in the word "damn" than in the word "degeneration."
G.K. Chesterton, Orthodoxy, VIII

Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.
William Strunk, The Elements of Style, III.13

Prefer the short word to the long.
Henry Fowler, The King's English, Ch. I