Start off by masturbating with a basic "fist" technique until you start to approach orgasm. At that point, form a circle with the thumb and middle finger of your dominant hand, and begin circling around just underneath your penis head. It will be very tempting to go back to the "fist" when orgasm is near, but go with the "circle jerk" until the end. The resulting orgasm will be explosive. If you want to test your will, start off with the "circle jerk" and go with it all the way until orgasm.