From Grammar Girl:
singular they: The AP Stylebook now allows writers to use they as a singular pronoun when rewriting the sentence as plural would be overly awkward or clumsy. Example: The Obama administration told public schools to grant bathroom access even if a student’s gender identity isn’t what’s in their record.
The style also allows writers to pair they with everyone in similar situations.
In stories about people who identify as neither male nor female or ask not to be referred to as he/she/him/her: Use the person’s name in place of a pronoun, or otherwise reword the sentence, whenever possible. If they/them/their use is essential, explain in the text that the person prefers a gender-neutral pronoun. Be sure that the phrasing does not imply more than one person.
his, her. AP style used to be to use he when gender is not known. This entry now refers to the entry on they, them, their.
. . . .
Oxford Comma (aka serial comma). The new Stylebook emphasizes that clarity is the bottom line. Although the normal style is to avoid the serial comma, use one if it is needed for clarity. This is not a style change, but a clarification because the editors noted that some writers were confused.
Link to the rest at Grammar Girl