Prince is signed first by making the ASL sign for 'P', and then tracing the 'P' across your chest like a Prince's sash.
Make the sign for the letter 'P' by taking your dominant hand and making it into a fist with you index finger pointing up, your middle finger extended at 90 degrees, and your thumb cradled between the two fingers. Then starting at your non-dominant shoulder, trace a path across your body to your dominant hip.
Royalty signs like prince often figure prominently in children's books. We help our baby understand the concept of prince, princess, king, & queen by tying them to the concept of boy, girl, daddy, and mommy.
Use the royalty flash cards together when you introduce the signs. The images with the different genders and ages will help illustrate the meaning of these four signs.