Doing Facebook for small business? It’s still alive, but the way it used to work is dying or nearly dead. Posting every day? That’s a fast track to burnout. Random boosts? Usually a waste of money.

With 21 million users, Facebook Dating is a secret hit, including among Gen Zers who use it for clout and content as much as for finding love. Twenty-one million users, actually. In November, for the ...