There is an entire sub sect of the martial arts community where the stated focus is “self-defense”. These are classes where there is some very impressive and fancy looking brutality going on, and it is marketed as self defense, but be careful.
Self defense is a very strictly defined course of action – defined by law.
Working in the industry of martial arts, I am invited regularly to attend various self-defense clinics and seminars. I rarely attend anymore. When I was younger, I attended many of these, and for many years I taught the very stuff I am warning you against now.
In one class, the instructor taught “what to do when confronted by a gun”. He taught us how to twist the gun out of the criminal’s hand, where to place the end of the barrel, and used the line “pull the trigger over and over until all you hear are clicks”.
To a twenty year old, this sounded like the coolest stuff in the world. Here I sit, twenty-one years later, and I am thankful that I did not encounter such a situation on the way home. For a start, the odds of getting shot while trying to take the gun away from the criminal are pretty high. But the legal ramifications to killing the assailant are too much to think about. Once you rip the gun out of his hand, you have to tread lightly. It becomes very easy to turn yourself into the bad guy once the threat to your personal safety is gone. In my years I have been taught how to take knives and guns away (good luck with that…), how to make the guy cut his own wrist, or throat, how to disarm him and then dislocate several joints to make it impossible for him to leave the scene, and on and on.
I say be careful. The first area of self-defense that you should look into is self-defense law. As this varies state to state and country to country, you will have to do some research on your own for this information.
Next you will need to understand fully that one seminar will not make you capable of protecting yourself in a violent situation. The brain works in a very complicated manner in a crisis, and most of what the brain does in a crisis in not going to help you get out of trouble. Humans have a triune brain. The reptilian brain knows eat, sleep, find a place to poo, and that is about all. It regulates breathing and all bodily functions and processes. The puppy brain operates at a higher level and can be trained to handle the crisis. The human brain is what we use day-to-day, but it also has a nasty habit of shutting down in a crisis situation.
You are not going to be able to train your midbrain to handle a crisis in one seminar, it will take months, and possibly years of practice.
Martial arts school owners know this. They use it as a selling point to get you from seminar to student member.
Be careful.
In most cases, martial arts are not self defense. To gain effective self-defense ability, you will need to train to handle the adrenaline dump that your body will enter into. Have you read the effects of adrenaline on the body? Time distortion, tunnel vision, hearing loss, and many other issues come into play. The biggest issues that most people would need to consider are loss of fine motor skills and loss of rational thinking.
Will you be able to perform your fancy wrist lock when you cannot control your fingers and your hands are shaking like the hands of a junkie? Even more real, will you be able to do anything after you poop in your pants? (it happens!).
Be careful in what you believe. Here are some links for further reading:

www.nononsenseselfdefense.com
www.conflictcommunications.com
“On Combat” by Lt. Col. Dave Grossman and Loren Christensen
“Surviving Armed Assaults” by L. A. Kane

Please look at the links and do your research. And be careful.