Great Rules for writing from William Safire in the New York Times

Do not put statements in the negative form. And don't start sentences with a conjunction. It is incumbent on one to avoid archaisms. If you reread your work, you will find on rereading that a great deal of repetition can be avoided by re-reading and editing. Never use a long word when a diminutive one will do. Unqualified superlatives are the worst of all. De-accession euphemisms. If any word is improper at the end of a sentence, a linking verb is. Avoid trendy locutions that sound flaky. Never, ever use repetitive redundancies. Also, avoid awkward or affected alliteration. Last, but not least, avoid cliches like the plague.