When self-defense becomes complicated, it's not self-defense.
In self-defense, rule number one is to stay safe. In order to do that, you have to be able to (in this order):
1. not be there in the first place (awareness and avoidance)
2. run away (get to safety)
3. pick something up to use as an improvised weapon
4. use your skills to stop your attacker and make sure they can't continue
Those first three things are really not complicated. The last one can be, depending on what a person is taught to do, but it shouldn't be.
Our philosophy for teaching self defense is to keep it simple. If it takes years and 1000's of reps to be good at, then it's not effective for real world self-defense. Self-defense needs to work for you today, not years from now, once or after you have mastered the move.
Honestly, it isn't complicated at all to push your thumb knuckle-deep in the bad guy's eye socket. That just takes the belief in yourself - that you are valuable and worth defending - and a will to do what it takes to make it home safe. What gets complicated is when you feel like you need to defend yourself against someone you care about or have a relationship with. That's where we find people freeze up. But that's for another blog post.
Too many times, we have seen "martial arts" teachers peddling complicated karate moves to new students that have so many steps or require that you do it "just right" for it to work. If you learn a move that requires steps "A-F" for it to be effective, what happens when the situation goes off the rails at step C?
I'm certainly not saying that complicated can't or doesn't ever work. If you have been training in a discipline for years, you can probably pull that stuff off. What I'm saying is that when we teach self defense classes, I never just assume that a student will return to train more. Sure, I want them to return. It is my hope they come back and do more. I also don't assume that the student will have or take the time to practice outside of the class I'm teaching that day. So the moves we teach have to work the day we teach them.
Also, to be truly "effective," the skills should be able to be used by the smallest, weakest, least athletic person, just as well as the biggest, strongest. That's why it's important not only what you learn, but who you learn it from.
Concept based systems are much more effective than technique based systems because you can apply concepts to multiple situations. As you search for a self-defense class, keep these things in mind.