William Safire's Rules for Writers:

• Remember to never split an infinitive.
• The passive voice should never be used.
• Do not put statements in the negative form.
• Verbs have to agree with their subjects.
• Proofread carefully to see if you words out.
• If you reread your work, you can find on rereading a great deal of repetition can be by rereading and editing.
• A writer must not shift your point of view.
• And don't start a sentence with a conjunction. (Remember, too, a preposition is a terrible word to end a sentence with.)
• Don't overuse exclamation marks!!
• Place pronouns as close as possible, especially in long sentences, as of 10 or more words, to their antecedents.
• Writing carefully, dangling participles must be avoided.
• If any word is improper at the end of a sentence, a linking verb is.
• Take the bull by the hand and avoid mixing metaphors.
• Avoid trendy locutions that sound flaky.
• Everyone should be careful to use a singular pronoun with singular nouns in their writing.
• Always pick on the correct idiom.
• The adverb always follows the verb.
• Last but not least, avoid cliches like the plague; seek viable alternatives.