Whether you're in danger or just fighting a fellow shopper for a pair of discounted wedges, every woman should know how to throw a solid punch.
The most important aspect to throwing a good punch is angle. Without getting your fist in the right angle first, any punching you attempt will be, at best, ineffective — and, at worst, you might end up hurting yourself.
To work on your angle, go grab a pitcher of water (or margaritas) and hold it out in front of you, with your arm relaxed and your elbow unlocked. Make sure that the top of the pitcher is below your shoulder. Start to pour the water (ideally, you'll do this over the bathtub) — the objective is to get a nice slow, steady flow before you've dumped out half of the water. When the water is flowing nicely, that's the hand position that you're going for. Practice this until you know exactly what your arm and hand should look like.
Now you're ready to practice your punch. Put down the pitcher and stand with feet shoulder-width apart, knees bent a little less than 45 degrees. Make a fist with both hands and bring both fists to your waist, fingers facing up, with your thumb across them. Your elbows should be pointing straight out behind you. In slow motion, bring your hand forward, rotating your fist until it has turned just past an upright position. Then drive with your top knuckle into the pitcher-holding position, extending your arm fully.
Continue practicing in slow-motion until the movement is fluid. Then, pick up the pace, timing the rotation of your knuckles to correspond with the extension of your arm. After each punch, pull your arm back, loosely flexing your elbow. Ideally, practice the punch against some hard pillows or couch cushions. If there's nothing to absorb the blow when your arm is fully outstretched, your elbow will have to take the full force. Hit those couch cushions a few times a week and you'll give Laila Ali a run for her money.