The gold standard. No more need be said than to quote Mr. Strunk's thoughts under the headline "Omit Needless Words":
"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 reader make all sentences short, or avoid all detail and treat subjects only in outline, but that every word tell."
And every word of Mr. Strunk's (as updated and expanded by the brilliant and self-effacing E.B. White) indeed does tell.
Don't touch your keyboard without reading this book!