You’re not alone if you’ve stared at a blank stack of wedding thank you cards and thought, “Do I really have to do this?” The answer is yes, but not in the way Emily Post's etiquette books ...

Unsurprisingly, birthday cards make up more than half of those sales. But thank you cards rank at third place, making the lack of options I encountered all the more confusing.

Etiquette expert Jan Goss agrees—so much so that she always carries a baggie of small thank-you cards in her purse. “Never pass up an opportunity to leave a thank-you note.

First, you should keep thank-you supplies stocked in your home office or your desk at work. A small box of note cards or stationary, postage stamps, and a pen are all you need.

They’re also fitting for a person who interviewed you for a job. Still, Ms. Pantzer advises common sense, to avoid getting sucked into a never-ending thank-you vortex.