When it comes to self defense, your best option is often to train in combat sports where you will have sparring matches with a fully resisting training partner and you will be putting yourself in advantageous positions (Takedown, mount, back control). Wrestling, Judo, Brazilian Jiu-Jitsu come to mind as viable options.
Grand Master Helio Gracie demonstrates his catalog of self defense techniques.
You can protect yourself in virtually any situation – from blocking a punch, or escaping a bear hug, to disarming an assailant with a knife, gun, club, bat, or chain.