This is for all the (other) pedants out there. None of the following is my own work! Thanks to the University of Minnesota's Centre for Writing:
Humorous Reminders of Common Writing Mistakes
1. Avoid run-on sentences they are hard to read.
2. Never use no double negatives.
3. Use the semicolon properly, always where it is appropriate; and never where it is not.
4. Reserve the apostrophe for it's proper use and omit it where it is not needed.
5. Verbs has to agree with their subjects.
6. No sentence fragments.
7. Proofread carefully to see if you any words out.
8. Avoid commas, that are not necessary.
9. When you reread your work, you will find on rereading that a great deal of repetition can be avoided by rereading and editing.
10. A writer must not shift your point of view.
11. Do not overuse exclamation marks!!! (In fact, avoid them whenever possible!!!)
12. And do not start a sentence with a conjunction.
13. Place pronouns as closely as possible, especially in long sentences, as of ten or more words, to their antecedents.
14. Hyphenate only between syllables and avoid un-necessary hyphens.
15. Write all adverbial forms correct.
16. Don't use contractions.
17. Writing carefully, dangling participles must be avoided.
18. It is incumbent on us to avoid archaisms.
19. If any word is improper at the end of a sentence, a linking verb is.
20. Steer clear of incorrect verb forms that have snuck into the language.
21. Take the bull by the hand and avoid mixed metaphors.
22. Avoid modernisms that sound flaky.
23. Avoid barbarisms: they impact too forcefully.
24. Never, ever use repetitive redundancies.
25. Everyone should be careful to use singular pronouns with singular nouns in their writing.
26. If we've told you once, we've told you a thousand times: avoid hyperbole.
27. Also, avoid awkward or affected alliteration.
28. Do not string a large number of prepositional phrases together unless you are walking through the valley of the shadow of death.
29. Always pick on the the correct idiom.
30. "Avoid overuse of 'quotation' 'marks.'"
31. Never use more words than are necessary to get your point across: be concise.
32. Awayz check you're spelling. (Your spellchecker would only pick up one of the two errors here.)
33. Always be avoided by the passive voice.
34. Every sentence a verb.
35. Last but not least, avoid cliches like the plague: seek viable alternatives.