I generally recommend avoiding places that advertise themselves as self-defense training services only. Jiu jistsu, muay thai, and krav maga gyms will often offer self defense classes alongside classes for them as a combat sport or fitness.

Those are also generally the only 3 that I would recommend for real self defense, and in that order.

It takes a lot of practice, but it's also a lot of fun, and great for fitness. But like said elsewhere, avoiding a real-world fight by running is always preferable.

That's also why jiu jitsu is the best for self-defense imo; it's not a striking style, it's all about grappling, and if you can't run, it's probably because you're being (or soon to be) grappled. And jiu jitsu teaches you not just how to grapple back, but how to escape grapples as well.

WRT weapons, pepper spray buys you time to run.

Single-shot tasers (e.g. C2) are another option, but should not be relied on, because they may or may not catch the skin (they have little tiny barbs that have to basically fish-hook into someone), or be deflected by clothing, etc.

Do not carry a "true" taser, with fixed leads (also called a stun gun; your standard 'movie taser) for self-defense. It vastly increases the likelihood of it being taken away and used on you. A single-shot taser (fired immediately on draw) may not stop them, but they can't turn it back on you.

Knives are for attacking people with, not defending with. If you really think a knife is likely to be used on you somewhere, don't be there. If you do find yourself facing down an attacker with a knife and you can't run, you want a gun, not another knife. People don't realize just how... I don't want to say fickle, but rather down to chance getting stabbed is. You could get stabbed 20 times and they end up all being relatively superficially, and survive, or you could get stabbed once and it knick something vital, and you die. Not every important piece of your body is inside your rib cage. There was a stabbing in a mall in I think Canada where a big guy gets stabbed by another dude very quickly, continues walking normally for a few seconds, and just collapses.

Finally, firearms.

Firearms can be very effective defensive weapons (obviously), but they are an entirely separate set of laws, skills, and circumstances to deal with.

I have mentioned elsewhere here that I actually provide firearms safety training, and I'll tell you what I tell a lot of people who come to me thinking I'm going to tell them to train and get a CCW permit: my firearms are not for out-and-about self defense.

I don't have a CCW and I don't carry, because the statistical probability that any given person will require a firearm ever in their life for self defense is so infinitesimally small, that you're actually much more greatly increasing your own risk by carrying it.

And to be clear, the main risk is not someone taking your firearm and using it against you (that would by definition be at most the same probability as encountering a situation in which you need to use it), the main risks of a CCW firearm are:

• negligent discharge, resulting in legal peril and risk to others
• losing the firearm, resulting in legal peril and risk to others
• improper deployment of the firearm (more often than not without even firing it, just brandishing), resulting in legal peril and risk to others

etc etc...