I don't remember where I picked these up but have found them invaluable down the years:
1. Verbs has to agree with their subjects.
2. Prepositions are not words to end sentences with.
3. And don't start a sentence with a conjunction.
4. It is wrong to ever split an infinitive.
5. Avoid clichés like the plague. (They're old hat.)
6. Also, always avoid annoying alliteration.
7. Be more or less specific.
8. Parenthetical remarks (however relevant) are (usually)unnecessary.
9. Also too, never, ever use repetitive redundancies.
10. No sentence fragments.
11. Contractions aren't necessary and shouldn't be used.
12. Foreign words and phrases are not apropos.
13. Do not be redundant; do not use more words than necessary;it's highly superfluous.
14. One should NEVER generalise.
15. Comparisons are as bad as clichés.
16. Don't use no double negatives.
17. Eschew ampersands & abbreviations, etc.
18. One-word sentences? Eliminate.
19. Analogies in writing are like feathers on a snake.
20. The passive voice is to be ignored.
21. Eliminate commas, that are, not necessary. Parentheticalwords however should be enclosed in commas.
22. Never use a big word when a diminutive one would suffice.
23. DO NOT use exclamation points and all caps to emphasise!!!
24. Use words correctly, irregardless of how others use them.
25. Understatement is always the absolute best way to put forthearth shaking ideas.
26. Use the apostrophe in it's proper place and omit it when itsnot needed.
27. Eliminate quotations. As Ralph Waldo Emerson said, "I hatequotations. Tell me what you know."
28. If you've heard it once, you've heard it a thousand times:Resist hyperbole; not one writer in a million can use itcorrectly.
29. Puns are for children, not groan readers.
30. Go around the barn at high noon to avoid colloquialisms.
31. Even IF a mixed metaphor sings, it should be derailed.
32. Who needs rhetorical questions?33. Exaggeration is a billion times worse than understatement.
34. The passive voice should never be used.
36. Do not put statements in the negative form.
37. Verbs have to agree with their subjects.
38. A writer must not shift your point of view.
39. Place pronouns as close as possible, especially in longsentences of 10 or more words, to their antecedents.
40. Writing carefully, dangling participles must be avoided.
41. If any word is improper at the end of a sentence, a linkingverb is.
42. Take the bull by the hand and avoid mixing metaphors.
43. Avoid trendy locutions that sound flaky.
44. Everyone should be careful to use a singular pronoun withsingular nouns in their writing.
45. Always pick on the correct idiom.
46. The adverb always follows the verb.
47. Be careful to use the rite homonym.And Finally...
47. Proofread carefully to see if you any words out