Wear your hair in a style that won't push up on the cap. Long, loose hairstyles or something in a ponytail work the best.
Spray the hair with a fine mist of hairspray. This gives the hair a bit of grip to help the cap stay in place.
Place the graduation cap squarely on your head. Do not angle the cap too far back or you will have to adjust it all day. Keep the cap as perpendicular to the ground as possible. If you have bangs or want to show a bit of your hair, place the cap directly behind that area.
Connect the cap to your hair with two bobby pins the same color as the cap. Form an "X" with the pins. Use as many as necessary to keep the hair and cap in place.