Suppose all oil is gone and the energy grid fails.
Suppose the dollar fails and is no longer excepted as trade.
Or even suppose that Zombie monsters or devils are coming to get you.
What do you do?
Your first priority is shelter
All your guns, food stock will be gone if you don't have a way to store it and keep it from predators. You can only stay awake for so long, and fight for so long. Eventually you will need a place to hit the hay.
If you're in your house good. Maybe see if there's a mass shelter, although this could be dangerous
depending on the circumstances.
Second priority is sustenance
This is a good source of water and food. Sometimes in a matter of mass hysteria, it would be okay to raid a store or abandoned homes.
If you research ways to clean water, get this going. Water is more important than food. You can go about 7 days without food, you can only go about 3 without water. Find ways to collect rain water, do you have gutters? There are techniques to gather the moisture in the air. Find ways to clean the water, there's ways (haven't looked into this) to filter it with sand and charcoal. If boiling is an option they say an hour boiling will kill all bacteria, even then is your source a river? It may have chemicals in it which resist the boiling and can still kill you.
Food. Eventually you will need food. This is second to water. If you have a gun, consider venturing into woods and hunting, catching a large animal will feed you for quite awhile. Start a garden if you haven't already. Save all scraps grind them up and mix into the soil. Consider raiding stores to gather supplies, although this can be dangerous as others will be there as well.
Third priority is defense
Less fortunate and less intelligent will no doubt be trying to steal and raid what you built. And if you think the worlds full of nice charitable people you probably wont live long. This is why defense is important. If you have friends or family, it's best to take shifts working/on guard so that you always have eyes on your property.
Get walls up around your property. If you have welding skills use them, concrete use them. But anyone can dig. Fill grocery bags with dirt or sand tie and stack. find old fencing too. But consider that a bad defense can reduce vision and actually be worse off then leaving your plane yard open.
Consider having someone posted on the roof of your structure at all times running different shifts. Have call signs if there are too many to remember all faces. Have rules of engagement strictly enforced and all members of your property know them. You need weapons, whether it's guns and ammo, or makeshift clubs and rubber band nail guns, you need them. People are assholes.
Clear obstructions that might allow an invader to get close to your property without you seeing them.
Generally it's good to have only two ways in and out of your property, one generally for entrance and exit, and one for evacuation.
Fourth priority is trade
Even once you get food, water, defenses up, there will be some needed things you just can't get. But you may have something most people can't get either. Trade is very important. If you have some nack or skill that not many have now is the time to practice it. I can make alcohol. I'm not a brewmaster but I understand and practice it, and I have the tools to do it. If your wife can make candles? Think without electricity how valuable they will be now. Soap? Anything you can make that is now a need will instantly be worth a fortune. The dollar is now worth nothing.
I know for a fact alcohol will be a great way to trade. It can be used to sterilize, or fuel engines and at the least people like to get wasted when life sucks.
There are other needs that I haven't mentioned, because they all depend on your place. Transportation might be a necessity if you live far away from anything, or want to get far away from something. Energy might be a necessity if you live in a cold area, but regardless you should strive to get a way to generate electricity for lighting and tools because you can only burn wood/candles etc for so long and it gets expensive.
Another important tip, always stay busy doing something, working have purpose. Or else you may start going BAT SHIT CRAZY !!!!!!!!!!!!!!!!!!!! lel