i personaly used to be a bmf i took several stages of K-5 in the marine core if you really want to kick some ass dont talk about it,
use your elbows, forearms,and the ridge of your palm,and a good roundhouse to the head works pretty well. a kick in the knee if done right will make your opponet sick to their stomach everytime stomp their foot with all your energy and you will break everybone in their foot(using only your heel) even if you are barefooted.
you can even use your shoulders and head as weapons and if they are face to face use an uppercut(using your palm)to the chin and follw through so when the back of their
head hits the ground you still have your palm on their chin and it over but dont try this unless you feel your life is threatend ,disable your opponet on the first blow then its your choice on how far you want to take it from there