Use a semicolon between independent clauses in a sentence when they are not joined by and, but, for,nor, so,or yet.

Ex.: On our first trip to Houston, I wanted to see the Astrodome; my little brother wanted to visit the Johnson Space Center.

Use a semicolon between independent clauses that are joined by a conjunctive adverb or transitional expression. 

Ex.: The popular names of certain animals are misleading; for example, the koala bear is not a bear.

A semicolon(rather than a comma) maybe needed to seperate independent clauses joined by a coordinating conjunction when the clauses contain commas.

Ex.: Our strongest defensive players are Carlos, Will, and Jared; and Kareem and Matt are excellent on offense.

Use a colon before a list of items, especially after expressions like "as follows or the following".

Ex.: Beyond talent lie all the usual words: discipline, love, luck, but, most of all, endurance.

Use a colon before a statement that explains or clarifies a preceeding statement.

Ex.: Lucas felt that he had accomplished something worthwhile: He had written and recorded his first song.

Use a colon before a long, formal sentence or quotation.

Ex.: Patrick Henry concluded his revolutionary speech before the Virginia House of Burgesses with these ringing words: "Is life so dear, or peace so sweet as to be purchased the price of chains..."

Use a colon in certain conventional situations.

Ex.: 1) Between the hour and the minute

Ex: 12:57 pm

2) After the salutation of a business letter

Ex: Dear Ms. Gonzalez:

3) Between the chapter and the verse in Biblical references + between titles + subtitles

Ex: Matthew 6:9-13