I wish I could say I made these up, but it would be untrue. Let me credit the uncredited source who put them on the Internet. These are more for formal writing than for fiction: but again, remember that to break the rules, you must know what the rules are.

1. Avoid alliteration. Always.
2. Never use a long word when a diminutive one will do.
3. Employ the vernacular.
4. Eschew ampersands & abbreviations, etc.
5. Parenthetical remarks (however relevant) are unnecessary.
6. Remember to never split an infinitive.
7. Contractions aren’t necessary.
8. Foreign words and phrases are not apropos.
9. One should never generalise.
10. Eliminate quotations. As Ralph Waldo Emerson said, “I hate quotations. Tell me what you know.”
11. Comparisons are as bad as cliches.
12. Don’t be redundant; don’t use more words than necessary; it’s highly superfluous.
13. Be more or less specific.
14. Understatement is always best.
15. One-word sentences? Eliminate.
16. Analogies in writing are like feathers on a snake.
17. The passive voice is to be avoided.
18. Go around the barn at high noon to avoid colloquialisms.
19. Even if a mixed metaphor sings, it should be derailed.
20. Who needs rhetorical questions?
21. Exaggeration is a billion times worse than understatement.
22. Don’t never use a double negation.
23. Capitalize every sentence and remember always end it with point
24. Do not put statements in the negative form.
25. Verbs have to agree with their subjects.
26. Proofread carefully to see if you words out.
27. If you reread your work, you can find on rereading a great deal of repetition can be avoided by rereading and editing.
28. A writer must not shift your point of view.
29. And don’t start a sentence with a conjunction. (Remember, too, a preposition is a terrible word to end a sentence with.)
30. Don’t overuse exclamation marks!!
31. Place pronouns as close as possible, especially in long sentences, as of 10 or more words, to their antecedents.
32. Writing carefully, dangling participles must be avoided.
33. If any word is improper at the end of a sentence, a linking verb is.
34. Take the bull by the hand and avoid mixing metaphors.
35. Avoid trendy locutions that sound flaky.
36. Everyone should be careful to use a singular pronoun with singular nouns in their writing.
37. Always pick on the correct idiom.
38. The adverb always follows the verb.
39. Avoid run-on sentences they look terrible.
40. Join clauses good, like a conjunction should.
41. About those sentence fragments.
42. Just between you and i, case is important.
43. Don’t use, commas, which aren’t necessary.
44. Its important to use your apostrophe’s correctly.
45. Correct spelling is absoluteley essential.
46. Last but not least, avoid cliches like the plague.