Here are some other elementary rules of usage:
Possessive
Form the possessive singular of nouns by adding an “s” (Mary’s house, Charles’s farm).
Exceptions are the possessives of ancient proper names ending in “s” (Moses’ and Jesus’).
Possessives, such as hers, yours, and its, have no apostrophe. (The shade stunted its growth). “It’s” is the contraction for it is. (It’s now growing in the sun).
Dash
A dash is a mark of separation stronger than the comma. It is often used for emphasis. Use only when a comma seems inadequate. (He heard someone cry out—an ear-piercing scream.) Be careful not to overuse dashes.
Subject/Verb Agreement
The number of the subject determines the number of the verb. If the subject is singular, the verb must also be singular. Use a singular verb form after each, either, everyone, everybody, neither, nobody, someone. (Someone left her purse in the grocery cart.)
Participles
A participial phrase at the beginning of the sentence must refer to the grammatical subject. Be careful not to leave your participles dangling. (On arriving in Atlanta, I discovered my luggage was missing.) Arriving refers to me and not to my luggage. It would be wrong to say: Upon arriving in Atlanta my luggage was sent to Miami by mistake.
These elementary rules of usage are taken from The Elements of Style and The Chicago Manual of Style. Both are excellent resources for grammatical tips.
“Vigorous writing is concise. A sentence should contain no unnecessary word, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts.” – The Elements of Style.