A colon (:) is used

1. After the salutation in a business letter
        Example: Dear Ms Willett:
2. To introduce a horizontal or a vertical list
        Example: The accident was caused by three factors: alcohol, severe windy conditions and faulty brakes.

A colon is not used

1. After such as or because
        Example: The food bank needs items such as canned goods, dry cereal, rice and pasta.
2. After a verb, especially parts of the verb to be (see Voice, Chapter 19)
        Example: Three reasons this world is not a better place are greed, prejudice and selfishness.

A semicolon (;) is used

1. To join items in a list that already uses other punctuation
        Example: The three planning groups will be Julia, Wes and Lou; Al, Sylvan and Tomas; and Jill, Fawzia and Gini.
2. To join two independent clauses in a compound sentence
        Example: The staff party will be held at the Holiday Inn; parking will be free.