Check each sentence to be sure it is not a

1. Run on sentence.
2. Sentence fragment.
3. Sentence that doesn't make sense.
4. Stringy sentence.
   (one that contains more than two independent clauses)

1. Be sure you've used the correct word.
2. Avoid slang words. (kids, homies, etc.)
3. Use precise nouns and verbs. (Word choice)
4. Avoid contractions in formal writing.

1. Be sure that subjects and Verbs agree in number. (singular or plural)
2. Be sure pronouns agree with their antecedent in number. (singular or plural)
3. Be sure pronouns are in the correct case. (subjective or objective e.g. between you and me)
4. Keep verb tenses consistent. (present, past, future, etc.)
5. Keep voice is consistent. (Don't switch incorrectly from first to second person, etc.)
6. Keep similar items parallel.
7. Use subjunctive mood for hypothetical and untrue situations.

1. Be sure all sentences have ending punctuation.
2. Check to be sure questions end with question marks.
3. Use commas after introductory words and phrases.
4. Use commas after items in lists except for the last item.
5. Use a comma in a compound sentence just before the coordinating conjunction. (FANBOYS)
6. Use commas to set apart non essential phrases, clauses and appositives.
7. Omit unnecessary commas.
8. Use a comma after a dependent clause when it comes before an independent clause.

1. Check for careless spelling errors including poor letter formation.
2. Avoid casual spelling such as cause for because and gonna for going to.
3. Remember that a lot is two words.
4. Begin each sentence with a capital.
5. Check homonyms to be sure you have spelled the one you mean (there, their, they're; where,were, to, too, two; your, you're)
6. Capitalize proper nouns including I.
7. Eliminate unnecessary capitals.
8. Check to be sure apostrophes are used in contractions and possessives.
   Source: http://7-12educators.about.com