Most self-defense boils down to common sense.

Don't walk down deserted streets.

Don't put yourself in dangerous situations.

Keep distance from shady characters.

If your wife and child are with you, don't stay out too late.

Don't hang out at bars late into the night, and if you are hanging out at a bar, avoid the loud *******s, the ones who look like they're looking for a fight, etc. And be careful whose chick you're talking to.

Be respectful.

Carry concealed weapons.

When all else fails, unleash hell. That's when Martial ARts are required.