Self-defense starts long before anyone throws a punch. The most useful skills involve spotting trouble early, creating distance, using your voice confidently, and knowing when getting away beats standing your ground.
That may sound less dramatic than the movie version of self-defense, but real life rarely provides perfect lighting, a choreographed opponent, or a convenient soundtrack. Police and security guidance consistently puts prevention, distance, escape, and calling for help ahead of physical confrontation. The goal is not to win a fight. The goal is to make sure the fight never happens, or to get out of it as quickly and safely as possible.