1. Always deliver what you promise.
2. Each pronoun should agree with their antecedent.
3. Between you and I, case is important.
4. Verbs have to agree with their subjects.
5. Don't be a person whom people realize confuses "who" and "whom."
6. Never use no double negatives.
7. A writer should not shift their point of view.
8. When writing, participle must not be dangled. Don't do it even if it's hard not to.
9. Join clauses good, like a conjunction should.
10. Don't write run-on sentences, you need to punctuate them properly.
11. About sentence fragments. Don't. Unless it's for effect.
12. In letter themes and reports use commas to separate items in a series as well as phrases and clauses when required.
13. Don't, use commas, that aren't necessary.
14. Its important to use apostriphe's in the right place's.
15. Don't abbrev. unless approved by the Associated Press Stylebook.
16. Check to see you any words out.
17. Try to never split infinitives.
18. Avoid using a preposition to end a sentence with. That's a practice up with which some readers will not put.
19. Parallel structure will help you in writing more effective sentences to express yourself more gracefully and its pleasing to your editor.
20. In my own personal opinion I think that an author when he is writing should not get into the habit of making use of too many unnecessary words that he does not really need to use.
21. Last but not least, lay off the cliches and mixed metaphors. They might kindle a flood if anger in your editor.
Yes, that's twenty one, but they all needed to be listed to properly answer this question. The errors in the sentences are all purposeful and intended.
I do hope this helped you. :)
