Ya I’ll spit out all the unique-to-me self defence tips I learned from my Jiu Jitsu class.
Crotch nose eyes throat. Attack em. If someone pulls you into a chokehold from behind use your back leg to stomp and drag your shoes down their knees/shins and lean forward to pull them off balance. Use your elbow and your entire body weight (whatever you can) into their stomach, swipe your cupped hand down like a wiper and slam their balls, then move forward as they hopefully let go and flick your hand outwards straight into their eyes.
Make as much noise as possible and absolutely book it away and run after this.
I did Krav, Jiu-Jitsu and Muy Thai for a while. The biggest take away for me was the confidence boost, knowing with 100% certainty what I and my body can do.
I looked great too, but that was secondary
Buuuuut on the downside, I broke my collarbone and tore a muscle in my shoulder and it’s never been quite right since. Take Krav seriously
Bluffing as in saying you’ve had training? That’s a bad idea.
A huge portion of martial arts is learning how not to use martial arts. De-escalating, removing yourself from the situation, choosing your battles. If you feel the need to bluff you’re almost always better off just walking away.
One of the big lessons in Krav is that every confrontation is deadly. Not could be. Not might be. Is. In the real world it can only take one lucky punch to kill someone, even if the person throwing that punch is completely untrained. Every opponent on the street is armed, dangerous, and actively trying to kill you if you’re being attacked- that’s the mentality
You avoid fighting in every capacity possible, it’s an absolute worst case scenario. But if you have to fight? You be incredibly violent, dirty, and lethal. You aim to maim your opponent and get to safety- because assholes that start fights tend to run in packs. From that perspective them thinking that you’re untrained in an advantage because they won’t expect it.
Tl;Dr, I would rather bluff that I can’t fight than let them know I can
To answer your second question, yes it’s worth it for everyone to learn some degree of self defense skills, if only for the physical benefits
I studied karate a while ago and have looked into self defense since.
I think the most important think is to learn how to control your emotions during any confrontation either using them to your advantage or learning how to calm yourself, heart rate, the adrenalin spikes etc.
Notice what your body is doing and work with it to either calm it or not be so uncontrolled.
I studied savate (French kickboxing) for a while, as well as some karate. The savate really did wonders for my flexibility and balance in a way that I didn't experience with the karate, and it also felt more applicable in the "real world" in the same way that krav maga and other close quarter / street fighting martial arts do.
To echo @TexMexBazooka, the real lessons were in de-escalation and knowing how to defend yourself decisively to enable escape from the fight. My savate instructor was very clear that any and every fight was a deadly one and that if he found out we fought instead of escaping he'd kick the crap out of us and then kick us out of the program.
I think there's also a benefit in learning how to take a hit, even though the goal is to avoid those. There are lots of body mechanics involved in fighting motions and practical experience taking and avoiding hits teaches you to recognize those movements automatically.
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