The KISS Grammar Basic Guide to Punctuation
[See also The KISS Approach to Teaching Punctuation.]

Note that Levels One and Two are intended for use with primary school children.

Levels One & Two

Punctuation and Capitalization

Punctuating Sentences

     Sentences should begin with a capital letter and end with a period, question mark, or exclamation point:

Molly wanted to go home.
Did Molly want to go home?
Molly, go home!

The names of specific people, places, and things should be in capital letters: Bob Murphy, New York State, Thanksgiving.

Commas are used

1.) to separate items in a series:

Tom, Bill, and Jerry went to the park.
Tom played football, ate a sandwich, and then went to a movie.
Bill found an old, dirty, uncomfortable jacket.
2.) to set off constructions, such as prepositional phrases, direct address, interjections, or nouns used as adverbs, that add additional information to a sentence:
Long ago, on a hill in Greece, Philemon and Baucis lived.
David, where have you been?
Gee, I didn't think it was important.
Monday, they went to see the doctor.
3.) to separate the parts of a date and the parts of an address:
I will meet you Thursday, May 13, 15 CousinJohn's house, 814 Maple Street, Akron, Ohio.

Use Quotation Marks around

1. the exact words that people said: Molly said, "I want to stay here."

Note that
1. a comma is used after words such as "said," and before the quotation, and
2. the closing quotation mark goes after the final punctuation mark.
2. a word that refers to the word itself and not to what it means: "Five" has four letters in it.

An apostrophe is used:
1. To show that something in some way belongs to someone: Anthony's house; Sharon's idea, the town's streets.
2. In contractions to show that letters have been left out -- 
We'll be there. = We will be there.
I'm going. = I am going.
It's here! = It is here!
'Til = Until

Level Two (S/V/C Patterns)

1. Quotation Marks: Use single quotation marks for quotations within quotations:

The serpent hissed, "I could have eaten that cat last night if he had not called, 'Watch, little cat, watch!'"
2. Commas: Do not put a comma between a subject and its verb, or between a verb and its complement, unless you have a specific reason for doing so. 

Incorrect: They were having fun and playing, football.


They delivered, once a week, milk and cookies.
[The commas set off "once a week."]

It was a boring, frustrating, and generally lousy game.
[The commas separate the series of adjectives.]

Level Three: (Clauses)

1. Punctuating Compound Main Clauses

2. Subordinate clauses at the beginning of a sentence are usually followed by a comma:

Since no one was there, Bill and Jolinda decided to leave.
You will find many professional writers apparently ignoring this rule, but some teachers and editors are fussy about it. Its real importance is to close the mental processing of the initial subordinate clause. In effect the comma tells the reader that none of the following words chunk to the preceding S/V pattern. 
     Note what can happen when the rule is violated. The following sentence is from William Golding's The Inheritors (NY: Harcourt, Brace & World, Inc., 1955, p. 19). Golding is describing an old woman who is about to cross a creek, using an old tree trunk as a bridge:
When she walked swiftly across the trunk scarcely stirred in the water.
The odds are that you read "across the trunk" as a prepositional phrase and were then confused when you hit "stirred" -- there is no subject for it. But look at what happens if we add a comma:
When she walked swiftly across, the trunk scarcely stirred in the water.
The comma automatically tells readers that there is no object for the preposition "across." As a result, we process "trunk" as the subject of "stirred." 
     In context, it is possible that Golding wanted the confusion. This part of The Inheritors presents a confusing view of prehistoric humans, in part from their own point of view. It might, however, simply be a mistake, by Golding and by his editors. (Even professionals make mistakes.) The point is that if you get in the habit of putting commas after initial subordinate clauses, you are much less likely to confuse your readers.

Restrictive and Non-Restrictive Constructions

     Clauses (and other constructions) that restrict or limit the meaning of the word that they modify should not be set off by commas. Clauses (and other constructions) that simply give additional information are usually set off by commas. Often, whether something is restrictive or non-restrictive depends on the context:

Restrictive: The man who stole the car got away.
Non-Restrictive: The man, who stole the car, got away.
The restrictive version of the preceding would be used if readers already knew that the car had been stolen. The clause "who stole the car" thus identifies (restricts the meaning of) "man." For example: "Two men robbed the bank. The man who stole the car got away." The non-restrictive version assumes that the identity of "man" is already clear. For example: "A man and a woman robbed the bank. The man, who stole the car, got away."

Parentheses  ( ) can be used to set off explantory or other non-restrictive information:
The door-sill of the cave shines with a row of golden beads (small lights, to guide the foot) -- it is irresistible. (Christopher Morley)

Level Four: (Verbals)

The subject of a gerund is written as a possessive -- with an apostrophe: Bill's reading the book surprised us.

Level Five: (Additional Constructions)

Appositives are often set off by commas, but they may also be set off by dashes.

The top of the hill, the objective of their hike, was a long way off.
The top of the hill -- the objective of their hike -- was a long way off.
Noun absolutes that function as adverbs are almost always set off by commas.
Suzanne, her hair glowing in the dim light, did not appear to be interested.