In 90% of street fights, first punch to the face wins, i avoid going to the ground in a street fight... as soon as the fight is inevitable and there's nothing you can do to avoid it, quick jab to the nose, trust me, their eyes tear up, they get all disoriented, chances are they will start swinging wildly so after the quick jab you need to shoot for a double leg and finish the fight on top however you feel is appropriate.