Insert a comma before a conjunction if the conjunction brings two independent sentences together. For example, the sentence "I have plenty of rest, and I expect to do a lot of work" is made up of two separate statements. Conversely, "I have plenty of rest and such" is not made up of two separate sentences, and no comma would go before "and" in that case.
Place a comma after an introductory word or phrase that comes before the main sentence. For example, the sentence "After a while, we sat and looked at the stars" has the introductory phrase "After a while."
Use the serial comma. A serial comma is a comma that separates a list of three or more words or phrases in a series and goes before the "and" or "or" conjunction. For example, "Red, blue, yellow, and green" is a series and each is separated by a comma.
Insert a comma before and after any word, clause or phrase that is not integral to the sentence. For example, in the sentence "I do not like granite counters, although they are durable, because marble provides a better finishing touch" the clause "although they are durable" is not integral to the sentence.
Place a comma before anything at the end of a sentence that refers to an earlier part of the sentence. For example, in the sentence "Bob was a competitive man, driven by his failures as a boy" the phrase "driven by his failures as a boy" refers back to Bob being a completive man.
Use a comma if the sentence reads confusingly or awkward without one. For example, the sentence "Day and night businesses fail all over the country" would need a comma before "businesses" to prevent confusion.
Apply the standard comma rules. Other than the above six rules, APA format follows standard comma rules, such as placing a comma after the date of the month.