Just a quick response I posted on Reddit that I am also sharing here (to Defending yourself abroad):
Not getting drunk at bars likely proactively addresses a significant portion of issues.
Second, if you are coming from the USA or many other fairly high personal crime countries there are many places you are much safer while traveling. If you are coming from Japan, Singapore, Scandinavia you probably are much more likely to be the victim of crime than at home.
If you are not drunk the most likely crime is theft, while not good, it is much better than being attacked in my opinion (at least much better than being attacked by someone who is the equivalent of your still ineffective kid brother :-)
The biggest concern in a new environment is that you don't pick up on the clues of danger that you would in your home environment. This means to be safe you are wise to try and develop the ability to be more skeptical and more attuned to what is going on around you. You may also be the target as you may be more visible, may be seen as rich, may be seen as a jerk (often being drunk helps boost this impression).
There is danger everywhere. But we often exaggerate the danger of new place (new to us). Being careful makes sense, but the dangers away from home are often statistically less though are unfamiliarity may lead us to be less aware and able to avoid situations we find in unfamiliar surroundings. Also, being on your own (instead of in a city with lots of friends that help keep you in line, give you protection in numbers in some situations...) can increase the risk to you, especially again in unfamiliar surroundings.
I doubt learning fighting skills makes much sense. Outside of drunken brawls most places are not that violet and if they are many times it is guns and such things (though most often that level of violence is aimed at other criminals or family and friends).
There is other violence (between people) of course and it is sad and something to avoid. I would be amazed if car and bus deaths (of travelers) and injury don't exceed by a long way any person on person violence against travelers.
Related: Curious Cat Travel Destinations - Travel Photos blog - A Tourist in Singapore - Curious Cat Australia Travel -