How do you win a fight?

Get a good feet stance behind one or you will get flawed to knock out/kill. Punch them in their chin and they will shake their heads to injury. Do hard jabs to the body or go for the groin area to stun them.

There is no way to guarantee a win. Everyone has the chance to get in a lucky punch. Being prepared, being fit and avoiding the situation is the best way to do it. If you do get in a fight, try to stay calm.
The best way is to avoid it. That way you both win.