if this is a playground fight its all about confidence, you gotta keep it together. if you look hard you'll see that he's shitting himself, that'll be a big confidence boost. just strut up to him and grab his head, by his ears or his throat, and nut him as HARD AS YOU CAN. its pretty easy to grab someones head, but if you dont get that chance jab/chop his neck, that'll instantly stop him, then you can go to work on him. if he throws any punches try and grab his fist, its pretty easy, then twist his hand away from him. untill it breaks/ he starts crying/ he appologises.
thats all i got.