they say to look at the bright side of someone, and that's it. ha!
look at the one value that the person is most insecure about, and hasn't tackled and keep it ready in your back pocket. never pull it out without a cause and start berating for no reason, otherwise you'll be the asshole.
just know what's on the card and flick it slyly as opposed to putting it in front of their face when you need to keep them in line.