When it comes to self-protection in wartime, we will simply analyze it from both external and internal aspects.
The first is external factors, that is, environmental factors.
Generally speaking, the outbreak of war has a purpose, in order to expand territory, for resources and so on. War itself is a consumption of resources, so more firepower will be concentrated on strategic goals, such as power plants, governments, signal towers and so on. Then, in order to survive the first attack, it is a wise choice to stay away from these dangerous buildings.
From the point of view just now, the primary attack target of the other side in the war should be able to cause group damage, so if you stay in a sparsely populated place, the possibility of being attacked will be greatly reduced.
Material reserves are also essential, because some survival materials will be extremely scarce after the outbreak of war, and at this time, if you are prepared before, you can at least have a basic survival guarantee for a while. Materials that can be stored include but are not limited to: food that can be stored for a long time, lighting, water and water purification devices, heating equipment, self-defense weapons, etc.
Then there are internal factors, that is, personal factors.
The law of nature is: survival of the fittest.
In peacetime, no matter how bad the living conditions are, there is a bottom line. Many people don't think life is difficult, but once the war breaks out, even if they are not on the front battlefield, life in the rear is absolutely extremely difficult. Then from the perspective of being prepared for danger in times of peace, we should also have a sense of crisis in this peacetime, and pay attention to accumulating some common sense and skills to survive in the harsh environment in peacetime.
Only the brain without the corresponding body can hardly survive in wartime, so exercise consciously (of course, even if you exercise all the time at ordinary times, it is beneficial and harmless).
The above is just a simple explanation of how to improve the survival probability when the war breaks out from two general directions, which is very general, because many books can actually be published on specific methods.
Despite all the preparations, our ultimate hope is: world peace, not war!