Heh, I forgot to stick in definitions and examples for those who don't 
know grammar terms.  If anything else is unclear, just ask.  :)

Sapphire, The Blue Tigress

*****

Use of comma:

1.  To separate items in a series.

This one's easy.  Just take everything on your shopping list and stick 
commas in between each item.

2.  To separate two or more adjectives preceding a nown.

The blond, blue-eyed woman cheered.

3.  Before _and_, _but_, _or_, _nor_, _for_, _yet_, when they join 
    independent clauses, unless very short.

Examples: I came and I conquered.
          He shoveled the snow off the driveway, and he drove to work in his 
          old Buick.

4.  To set off nonessential clauses and nonessential participial phrases.

Participial phrase:  Carrying a large package
(basically a phrase starting in a verb that ends with '-ing')

Clause:  I came
         that stood there
(The first one is an independent clause. The second one is a dependent 
clause.)

5.  After certain introductory elements,
    (a)  After words such as _well_, _yes_, _no_, _why_, etc., when they 
         begin a sentence.

Example:  No, I don't know.

    (b)  After an introductory participial phrase.

Example:  Carrying a package, he came to the door.

    (c)  After a succession of introductory prepositional phrases.

Example:  By chance, he found the treasure.

    (d)  After an introductory adverb clause.

Example:  Before we leave the party, we must thank the hosts.

6.  To set off expressions that interrupt the sentence.
    (a)  Appositives

Example:  Jim, my son, goes to that school.

    (b)  Words in direct address

Example:  "Jim, close the door."

    (c)  Parenthetical expressions

(An explanation or comment that interrupts a sentence.)

7.  In certain conventional situations.
8.  Wherever it may be needed for emphasis or clarity, whether or not one 
    of the above rules applies.
9.  Do not use unnecessary commas.


Use of semi-colon:

1.  Between two independent clauses not connected by a coordinating 
    conjunction.

Coordinating conjuctions:  and, but

Example:  Her eyes opened; she looked around.

2.  Between independent clauses joined by conjuctive adverbs.

Example:  He liked beans; whereas, she hated beans.

3.  Between items of a series if they are already punctuated internally 
    by commas.

Example:  Sacramento, California; Boston, Massachusetts; Baltimore, Maryland

4.  To separate independent clauses if there are commas within clauses.


Use of colon:

1.  To mean "note what follows."

(like the Example: I've been using)

2.  Before a long formal statement.
3.  Between independent clauses when the second clause explains or 
    restates the idea in the first.