I think in most situations you have to go over your reasoning before you take action. Maybe 10% of the time you do go out you're not given the option to consider the reasons of a given situation.
When I go out I expect nothing to happen, that way if something does I have a little time to assess the situation. Whether its better for me to leave, or to fight.
I always see fighting as a last resort. I can easily call in a few favors. Believe me when I say I have a whole host of people who would either back me up on principle or because of finding out my history of when I grew up. I don't want their pity. Besides a few minor flaws I can do just as well as the next person.
When you examine the reasoning then you can decide your next step of action. I walk away most of the time. Here is an example from my life.
Awhile back I met 2 girls, at my little local bar. Asked them if they were going to this other one we went to. So I follwed them, and immediately ran into trouble. There was another guy who was talking to them, and he came over to me and told me to stop talking to them, or else I was going to get my "***" kicked. Then his brother came over, and told me that he, that guy I was having problems with, and all their friends were going to beat my ***, and they seemed more interested in him than me.
Then the dudes brother goes "Hey but you can do what you want." So my buddy was the dj that played the music over there so I said hey man I'm not putting up with this ********. I'm gone.
It could have been really easy for me to tell that guy those girls wanted me to talk to them which I did. But he wasn't going to follow any reason. So before it got out of hand I left. Incidentally I do not go back over there anymore.
I could have fought them, and won. But that would have not solved anything and I'd be going to jail because all of them would be calling the ICU their new found home. I took the smart road, and left. Leaving to go see another friend of mine.
Sorry for the long post but examining the reason before deciding on the action is also a good approach to take. Good points in the rest of the posts also.