Stuck on what to say? Here’s what to write in a birthday card for a friend, coworker or that special someone in your life.

It’s never as easy as a wishlist: Finding a gift for mom entails deciphering the cryptic clues that she drops (in between her insistences that she “really doesn’t want anything”).

Whether she’s your older sister, a sister-in-law, or your bestie who’s like a sister, there’s a birthday wish here that’s ...