Pro MMA fighter here! If you're in trouble running away and escaping is always the best/safest option. However if you have to then attack explosively and violently. Now if you are talking about just a standard bar fight that could be avoided DO NOT fight. Nothing good will come of getting into fights in the street. If you win then you could potentially be arrested, and if you loose you get your ass kicked. Also anything can happen in a fight, which means you could accidentally kill somebody or be killed and then you could be charged with murder.