The days of two unarmed people fighting each other are long gone. Second, the loser of the fight usually goes to the hospital and the winner of the fight usually goes to jail. While the jailed individual might eventually be released without charges, he nevertheless has to endure the inconvenience and indignity of being locked up. No one benefits from these fights. The best way to avoid bar fights is to be aware of your surroundings.
Some locations have reputations for having trouble.
Avoid these places. When you are inside a lunge or nightclub, be aware of the people around you. Generally, people who are looking for trouble will telegraph their intentions. They will attempt to stare you down, talk about you loudly enough that you can overhear them, and insult you. When this happens, move to a different location and notify the staff.