2. Do not use the common and grave forms of the personal pronouns in the same sentence; as, Thou wilt do this whether you wish or not.
3. Avoid the use of personal pronouns where they are unnecessary; as, John, he did it, or Mary, she said. This is a frequent error in speech.
4. Let the antecedent of each pronoun be clearly apparent. Note the uncertainty in the following sentence; He sent a box of cheese, and it was made of wood. The antecedent of it is not clear. Again, A man told his son to take his coat home. The antecedent of his is very uncertain. Such errors are frequent.
In relative clauses this error may sometimes be avoided by placing the relative clause as near as possible to the noun it limits. Note the following sentence: A cat was found in the yard which wore a blue ribbon. The grammatical inference would be that the yard wore the blue ribbon. The sentence might be changed to, A cat, which wore a blue ribbon, was found in the yard.
5. Relative clauses referring to the same thing require the same relative pronoun to introduce them; as, The book that we found and the book that he lost are the same.
6. Use but that when but is a conjunction and that introduces a noun clause; as, There is no doubt but that he will go. Use but what when but is a preposition in the sense of except; as, He has no money but (except) what I gave him.
7. Them is a pronoun and should never be used as an adjective. Those is the adjective which should be used in its place; as, Those people, not, Them people.
8. Avoid using you and they indefinitely; as, You seldom hear of such things, They make chairs there. Instead, say, One seldom hears of such things, Chairs are made there.
9. Which should not be used with a clause or phrase as its antecedent. Both the following sentences are wrong: He sent me to see John, which I did. Their whispering became very loud, which annoyed the preacher.
10. Never use an apostrophe with the possessive pronouns, its, yours, theirs, ours and hers.