1. Commas, commas, and more commas

2. Beware of popular myths of comma usage: MYTH: Long sentences need a comma. MYTH: You should add a comma wherever you pause. MYTH: Commas are so mysterious that it's impossible to figure out where they belong!

3. FANBOYS (coordinating conjuctions: for, and, nor, but, or, yet, so)

4. Introductory bits Adverbs/adverb phrases
Generally, extraterrestrials are friendly and helpful.
Moreover, some will knit booties for you if you ask nicely.
In fact, Godzilla is just a misunderstood teen lizard of giant proportions.
Throughout his early life, he felt a strong affinity with a playful dolphin named Flipper.
Adverbial phrases
If you discover that you feel nauseated, then you know you’ve tried my Clam Surprise.
As far as I am concerned, it is the best dish for dispatching unwanted guests.
Participle phrases
Kneeling down on one knee, Tom tried to explain Katie why he donated all of their money to scientology.
Bitterly disappointed, she filed for a divorce.

5. The comma splice
BAD: My hamster loved to play, I gave him a hula-hoop.
ALSO BAD: You wore a lovely hat, it was your only defense.
To fix these comma splices, you can do one of four simple things: just
add FANBOYS, change the comma to a semicolon, make each
clause a separate sentence, or add a subordinator (a word like
because, while, although, if, when, since, etc.)
GOOD: You wore a lovely hat, for it was your only defense.
ALSO GOOD: You wore a lovely hat; it was your only defense.
STILL GOOD: You wore a lovely hat. It was your only defense.
TOTALLY GOOD: You wore a lovely hat because it was your only defense.

6. Fanboy fakers Compare:
However, therefore, moreover, and other words like them are not FANBOYS (they are
called conjunctive adverbs/adverbial conjucts). They can go between two complete
thoughts, just like Fanboys, and if they do, they take different punctuation.
GOOD: Basketball is my favorite sport. However, table tennis is where I excel.
ALSO GOOD: Basketball is my favorite sport; however, table tennis is where I excel.
BAD: Basketball is my favorite sport, however table tennis is where I excel.
ALSO BAD: Basketball is my favorite sport, however, table tennis is where I excel.
Compare:
Good: Most of them, however, do try to act friendly and courteous.
(here ‘however’ is not a fanboy faker)

7. X,Y,and Z Put commas between items or phrases in a list.
EITHER: You can buy life, liberty, and the pursuit of happiness in Los Angeles. OR: You can buy life, liberty and the pursuit of happiness in Los Angeles.
BUT ALWAYS: A good student listens to his teachers without yawning, reads once in a while, and writes papers before they are due.
Series of adjectives:
He was a bashful, dopey, sleepy dwarf.
Series of adverbs:
Try to work quickly, confidently (,) and efficiently.
Series of phrases:
We spent an enjoyable day visiting the zoo, rowing on the lake, and picnicking in the park.

8. Interrupters (insertions, afterthoughts, non-defining relative clauses)
Bob Mills, a sophomore from Raleigh, was the only North Carolina native at the Japanese food festival in Cary.
Aaron thought he could see the future, not the past, in the wrinkles on his skin.
My chemistry book, which weighs about 100 pounds, has some really great examples.
To see if you need commas around an interrupter, try taking the interrupter out of the
sentence completely. If the sentence is still clear without the interrupter, then you
probably need the commas.

9. Miscellaneous: Use a comma…
to separate tag questions from the rest of the sentence.
You did that on purpose, didn't you?
to separate words and abbreviations that introduce an example or an illustration, including namely, that is, to wit, i.e., e.g., for example, and for instance.
Many of my friends, for example, Fred, Dean, and Pete, like to golf.

10. … to separate contradictory phrases from the rest of the sentence.
It was Betty, not Joan, who was elected queen of the prom.
to separate names used in direct address or other isolates such as yes, no, and thank you from the rest of the sentence.
Tell me, John, did you vote for Joan?
No, I am not voting for myself.

11. …
to separate nonrestrictive clauses, phrases, and appositives from the rest of the sentence.
The scout leader, overweight and out of shape, trudged up the hill.
to separate names of titles or degrees that follow the name.
Harold Johnson, Ph.D., will speak in the Commons on Tuesday.

12. …
to separate the names of smaller geographic units from the names of larger units.
Denver, Colorado, is called the Mile High City.
to separate items in a date. Omit the comma when just the month and year or month and day are given.
Kennedy was assassinated November 22, 1963, in Dallas, Texas.

13. John said, "The fishing is great in Bear Lake.“…
to separate direct quotations from the phrase identifying the speaker.
John said, "The fishing is great in Bear Lake.“
“The fishing,” John said, “is great in Bear Lake.”

14. …
to provide clarity and prevent misreading, even if none of the other rules apply.
We left him, assured that he would fail.
(We were sure that he would fail.)
We left him assured that he would fail.
(He was sure that he would fail.)

15. Congratulations! You know how to use commas.
But remember…when in doubt, leave them out!
PPT based on Diana Hacker Rules for Writers, the English Sprachpraxis Handout ‘Punctuation‘, and a website of the University of North Carolina.