24 Rules for Grammar and Style

1. Follow the basic subject-predicate word order for sentences: subject, verb, indirect object, and direct object.
2. Make sure sentences have both a subject and a predicate and express a complete thought.
3. Respect sentence boundaries. Do not let two or more independent clauses run together.
4. Keep modifiers as close as possible to the words they modify.
5. Use parallel structure for any series of actions or items or the not only/but also construction.
6. Make sure verbs agree in number with their subjects.
7. Keep the verb tenses consistent.
8. Use the correct subject or object form of personal pronouns. Determine whether a pronoun is functioning as a subject or object in the sentence.
9. Use apostrophes with pronouns to show contraction only. Pronouns do not need apostrophes to show possession.
10. Use who for people, use that for things, and which for nonessential clause that do not refer to people.
11. Make sure pronouns agree in number and person with their antecedents.
12. Be consistent in pronoun point of view.
13. Use less (meaning a smaller amount) for singular nouns representing quantity of degree. Use fewer (meaning a smaller number) for plural nouns and countable items.
14. Use good and bad to modify nouns and pronouns; use well and badly to modify verbs.
15. In comparisons, add -er or -est to short modifiers. For longer words, use more/the most or less/the least before the modifier.
16. Do not use double comparisons.
17. Do not use double negatives.
18. Use idioms correctly.
19. Be concise. Avoid unnecessary repetition and wordiness.
20. Be precise. Use exact words.
21. Avoid ambiguity. Make sure word choice and pronoun references are clear and modifiers properly placed.
22. In general, use an active voice.
23. Use variety in sentence structure.
24. Avoid jargon and pretentious language.

Hope this can be useful for you.

And as always, rules are meant to bend, not broken.