I have gotten in a few fights and I have a black belt, punched 928 on the punching bag machine as well as knocked some one out cold one punch and here is my advice:
There are only few situations that will result in a fight and they are 99% the result of a woman or a bar fight.
Punching and blocking are muscle memory actions and if you have never thrown a punch, blocked or dodged you will stand to get your ass kicked.
The best deterrent is to not have a dumb/selfish/useless GF or make a serious ass of yourself at the bar. Know how to punch, punch hard. Don't pick fights you can't stand to lose and always stand on some sort of higher ground that you can take advantage of; know your enemies weaknesses and know your strengths (at least have strengths) lol :/ lose teeth / brain cells w/e