If you pay attention to what the "prepper experts" tell each one of the preppers, it makes a lot of sense. From what I have learned is you prepare for whatever YOU think might happen. However, they all seem to recommend the following:
1) Adequate food supply.
2) Bug out equipment, bag in case you have to bug out.
3) If you are going to bug out, adequate caches if needed along the way.
4) Adequate defense. Some preppers didn't have guns, and they were recommended.
5) Barter items, silver, extra supplies, etc.
6) A secure underground bunker or basement.
7) Prepping neighbors.
Prepper friends and community, try to include a doctor, and other people with skills to rebuild society, welders, carpenters, mechanics, electricians, nurses, vets, supporting family members.
9) Adequate water supply or filtration system, portable, and/or a well.
10) Adequate medical supplies and medicines which includes masks, gloves, and suits in case of a pandemic.
11) Have a "ham" radio as well as an emergency radio.
12) Adequate power supply, generator, solar cells, windmills, etc. Have 12 volt power system. This will be needed to operate radio's and power tools, and maybe freezers and LED lights.
13) Adequate sewage and/or waste disposal system, outhouse, septic tank if adequate water supply.
14) Keeping vehicles filled with fuel in case of bug out and have your secure location within range of one tank full.
15) Having several alternate routes with maps to your secure location away from heavily traveled areas.
16) Keep your mouth shut about prepping unless you can trust them to agree and be preppers themselves.
17) Practice with your weapons at least once or twice a week to keep fully familier with your weapon(s) in case they are needed.
18) Have an adequate supply of ammo, cleaning supplies, and spare parts for your weapons.
19) Have adequate hand tools for in case of long power outages and/or no fuel for generators.