Gotta agree with Art of some of his points.
IMHO, martial arts forms a good foundation for more learning. It shouldn't matter what you study.
From there you need to learn how to fight. And that involves mindset and aggresivness. It also requires knowledge. It is very helpful to understand human anatomy, and human nature. Learn to read the signs in your opponent, study the effects of alcohol and drugs, figure out if the guy's been in prison etc.(tats) Is he a grappler, a western style boxer, or a MA type. If he's hardcore he will be a streetfighter, which is what you need to do.
Ultimately, you want to hit his weak parts with your strong hard parts, and damage his body as quickly as possible. Absolutely explode into him and unleash a barrage of damaging blows that in combination will cause him great pain, disable him or simply knock him out.
It's amazing what kind of horrible damage bare hands and boots can do to the human body with a couple simple, unexpected blows. Fight won.