How to defend with proper punching form

All punching techniques, whether you are throwing a jab, hook, upper cut or power punch, must be delivered with proper form. Not only will proper form maximize your power and efficiency, it will also lessen the risk of injuring yourself. The two knuckles that you use in all punches are the base of the index and middle fingers; those that appear on the top if you made a fist with your palm to the ground. The main reason why traditional martial artist training included knuckle push ups was to teach proper punching form. Doing push ups balanced on just those two knuckles requires the proper alignment of your arm from the two knuckles right back to the shoulder.
Try making a proper tight fist by rolling your fingers up as tight as possible with your thumb folding over in front of your index & middle fingers. See the video to make sure you've got it right. Put your two punching knuckles (index and middle finger) on the floor, I suggest on carpet for starters. Set yourself into push up position and try a few push ups. Remember to be right over top of those two knuckles and those two only. In fact, you should be able to see which knuckles took most of the pressure by which ones are white when you get up. Another key is to have your fists as tight as possible, if they are not it will seem easier to do the push ups but your form will be wrong and the lesson lost.