4. Be the carotid kid
The carotid artery is the only place in the body where, if struck right, you can knock a man down, unconscious. The problem is if you miss. A great thing to do is to practice on a punching bag at a gym (with the bag set at the height of a man), hands up in defensive position, using the knife-edge of hand. The idea is to strike on side of neck, down on a 45-degree angle. Please note that this is dangerous, in that you could kill your attacker.