George Carlin suggested this one for a tattoo on a person's back:

Please, let's not tell this guy what we wrote on his back.
He thinks it's a sailing ship!

Seriously, once you have settled on a design put it in a drawer. Take it out a year later and, if you still really want it, have it put on. Balance a year of not having the tattoo against the likelihood that you will spend a lifetime with a tattoo that you no longer want.

Dr. Tattoff isn't getting rich without reason!