Those are some very good replies to your question. I cldnt agree more with Jason and Ted. Anyhow, to illustrate some points, take a look at tis video if you havent:
Observe how the big guy took his opponents. He went straight in one at a time (I cldnt help noticing how badly he punched but well, it worked for him). Also, notice the part in which he took one guy down with a wrestling styled move but did not enter into grappling range - instead he got right up and turned around in anticipation of the other attackers.
Check out his atttitude during the fight, though it may seem like he was the one who initiated the fight, its interesting to note how he gained the edge by his body actions - removing his shirt to show tt he's not submitting, and by charging right in with his animal instinct.
Body language is impt if you've chosen fight over flight, actions like rolling up ur sleeves or taking off ur shirt may make u appear intimidating as opposed to looking away with heads bowed (ala pizza palor attack).
Btw, theres another video tt i found interesting: http://www.big-boys.com/articles/oldmanfight.html
The old guy actually fell the first 2 guys tt attacked him.