"Use a single space after a period.
Do not use commas before a conjunction in a simple series. Example: In art class, they learned that red, yellow and blue are primary colors. His brothers are Tom, Joe, Frank and Pete. However, a comma should be used before the terminal conjunction in a complex series, if part of that series also contains a conjunction. Example: Purdue University's English Department offers doctoral majors in Literature, Second Language Studies, English Language and Linguistics, and Rhetoric and Composition.
Commas and periods go within quotation marks. Example: “I did nothing wrong,” he said. She said, “Let’s go to the Purdue game.'"
Credit: Owl at Purdue, Associate Press Style
"Hyphen: Hyphenate compound adjectives only if required for clarity: “fastest-growing company”; “high-level discussion.” Don’t use hyphens with commonly understood terms, adverbs that end in ly and between figures and units of measure: “greatly exaggerated claims”; “2 percent rule.” Do not use a hyphen with a compound modifier after the noun: “The driver was well paid.”
Dash: Dashes set off a series within a phrase: “Of the many breakfast options — omelets, waffles, pastries — he only wanted coffee”; indicate a break in thought: “Felipe’s is a popular eatery — in Harvard Square”; or attribute a quotation to an author: “‘You must do the thing you think you cannot do.’ — Eleanor Roosevelt.” When using text editors that don’t support dashes, use two hyphens for each dash.
Comma: In lists of three or more items, do not use a comma before the conjunction: “The recipe called for flour, butter and foie gras.” Exceptions are made if the elements in the series are complex phrases or if the series includes an element with a conjunction: “He doesn’t eat anything but pizza, Twizzlers, and macaroni and cheese.” Use a comma to set off a person’s town of residence, age and other such information: “Tom Menino, Boston, was a popular speaker”; “Jean Dupont, 32, was released yesterday.”
Period: Use only one space after the end of a sentence. Period.
Colon: Capitalize the first word after a colon only if it’s followed by a complete sentence. Colons go outside quotes unless they’re part of the quoted material.
Apostrophe: An apostrophe indicates possession. Add an ‘s to all single nouns and names, even if they already end in an s: “My boss’s vacation begins tomorrow.” For singular proper names ending in s, use only an apostrophe: “Kansas’ crisis.” For plurals of a single letter, add an apostrophe and an s: “Mind your p’s and q’s,” “the Oakland A’s.” Do not use apostrophes for decades or acronyms: the 1990s, CDs.
Quotation marks: Periods and commas go inside quote marks: “‘Reginald, your hairstyle makes me nervous,’ she said.” The position of dashes, semicolons, exclamation and question marks depends on what’s being questioned or exclaimed: “Was she right to say, ‘Your shoes are a joke’?”
Parentheses: AP style suggests avoiding parentheses when possible, and instead rewriting text or using dashes or commas to set off the information. If parentheses are required the rules are: If the parenthetical is a complete, independent sentence, place the period inside the parentheses; if not, the period goes outside."