In a series, place commas after each item but not before the final and.
In a quotation, put commas and periods inside quotation marks. (See the Quotations section.)
With a long descriptive title, put commas after the name and job description.
With degrees and long descriptive phrases, put a comma between the name, the degree, and the phrase.
When writing a specific date that includes the day of the week, put a comma between the weekday and the month, and between the date and the year.
For more information on commas, see the CP Stylebook.