Rules for stoppies:
1. Engine running, in gear
2. Lean forward, snap the brake lever. Practice this starting with a weak
snap, and make it progressively stronger until you know how hard to hit the
brake.
2.5 Modulate the brake, throttle, and body positioning to maintain the
stoppie while rolling. This is the fun part!
3. If you start going over, whack the throttle open. This will try to
bring the back end down. Jumpers use throttle modulation to stabilize their
attitiude in flight. Think about how a wheelie works and you will
understand.
4. Unfortunately, it is a lot more difficult to recover from riding a
stoppie than riding a wheelie. I would suggest if you can't ride a good
wheelie, and don't know how to balance yourself well, do NOT try doing
stoppies unless you do the little girly-man ones.