Nothing will teach you unarmed self-defense better than a GOOD martial arts school. (Or getting into "real" fights, I suppose.) I thought I was a badass until I took my first martial arts classes in high school. After trying a few styles, I ended up studying Muay Thai kickboxing for a number of years. Learning how to strike is one thing, but placement of development of that strike are probably 80% or more of the action. Also, learning to take a punch is helpful. And I don't mean hurt yourself until it don't hurt no more; you LEARN how to take a punch, which muscles to tense, how to shift your body so the other guy's hit lands in a less vital area, etc.
There are tons of styles if you prefer to punch, kick, holds and locks, or any combination. Kenpo can teach you some MEAN holds and locks. Ninjutsu is a real martial art too, not just in fiction. Difficult to find an instructor, but the fighting style is almost indefensible if you are serious. Thing is... they like to break bones!