The vast majority of the world has no system in place like developed countries do, and they will be hit hard. The one thing they do have though, that we tend to not, is the ability to operate without regularly functioning luxuries like we are used to. I am no survivalist guru, but with 20 years of military and intelligence experience and study, coupled with extensive travel and living in some of the most austere regions of the globe, this is my advice for the average American.
Panic buying toilet paper and hand sanitizer is not a solution long term. Though building a bunker and stocking guns may be a bit extreme on the other end; planning for 2-8 weeks of limited civilization, likely under government enforced curfews and aid delivery, is more reasonable for the average American.
Prepare to operate without toilet paper, that means having a hose or bidet-like solution. For the record, the vast majority of the rest of the world does this already as standard. Americans do not, and it will come to bite them in the ass (pun intended). Grabbing now the tools and equipment for this should be fairly easy - you can see some directions here.
Instead of panic buying absurd things, try to focus on stable items that will last, and that you will eat anyway. Aim for pasta and rice. Plus-up your seasonings and some canned goods like tuna and sauces to provide some diversity. I once lived off trail mix for a week on the island of Socotra off the coast of Somalia. Trust me, even tasty trail mix begins to taste bad after a few days.
Law Enforcement and Military will likely be providing security, but people tend to do crazy shit when they think it's the apocalypse. So relying on them to handle minor things like break-ins and theft is not wise. Ensure your locks and security systems are up to date and used. Run through security methods and reactions with your household now. What to do in case of a home intruder, what to do in case of a fire, what to do in case of a medical emergency. This can be done in as little as a couple hours. Do some role play with it to engrain this in your family's brains.
It would be wise to have ample sources of light on the offhand chance of a follow on disruptions - say, everyone in your neighborhood sitting home using air conditioners and the power goes out. It is not some prepper madness, to ensure you have some chemlights, flashlights and batteries. be prepared for power to go out for up to 24 hours. Chemlights are cheap and effective. But if you have kids who eat tide pods, please ensure they don't eat these - no they will no glow if they do.
If you can take out enough cash, for an emergency it is recommended. This does not mean making a run on the banks. This means, have say $500-$3,000 depending on your financial situation, in cash, in a safe place.
Ensure you have bleach. You can go all full prepper mode and get a LifeStraw or water sanitization tablets (I have) but for the average American just knowing the bleach-to-water ratio for cleaning water to drink is enough in case we have a water disruption for any reason. Read about it here.
The economy was doing great, but still many Americans are in no great condition financially. Prioritizing your needs with your resources is critical. If someone requires medication, that should be your first thing you try to stock up on now. Doctors can prescribe 90+ day amounts if you are going overseas or on vacation. I imagine, explaining that you are doing something like that, should be able to get your a prescription for that.
I am a fan of sticking through with investments currently, as I feel the economy will rebound, but you you should review what your current expenses are, and see which ones you can turn off. Clearly Amazon Prime Video and Netflix are required. We are not savages.
However, if you have some luxury expenses, especially recurring, say those stupid monthly box programs with "Guy Stuff" or whatever, it may be wise to pause these sorts of things for now depending on your financial situation. It took months to years even, for the economy to rebound after 2001 and 2008, begin preparing for this now just in case. Austerity is key.
Contact your family members now, and confirm what their plan is if things continue on this glide path. Will they stay at home and hunker down, or will they opt to depart urban centers for the summer house in the rural areas? Have the plan decided already. Confirm your loved ones also have or will prepare as noted above.
Most planning does not require a massive military planning team - it just requires a conversation hitting some key points and making a short To Do list. Just running through what situations may arise 2, 4 or 6 weeks from now is more than most do their entire lives.
Knowing that public and private services work fine, until 50% of the workforce is in bed with a fever, changes your outlook greatly. So, get your house together. Clean out the trash, organize your stuff and assume you will likely be providing services for yourself.
Ensure you have an SMS or online messaging group set up for your loved ones, and your neighbors. This ensures rapid collaborative communication in case of an emergency. Check with your neighbors to have a conversation on plans and see if they need help with something. A family member, friend or neighbor, rapidly becomes a liability for your if they did not plan.
Prepare your will. Do not be daft. You should have one anyhow. If not, I do not recommend going out and searching for lawyers now. You can do this all online in a short period of time for a fee, over at LegalZoom. Take serious stock in your relationships and use this time to get on a call or video chat or email follow ups with your friends and loved ones.
Stay the fuck home. Read your books. Work on the six-pack abs you always wanted since you ordered P90x that night drunk back in 2011. Watch your health. Both physical and mental. Take your Flintstones, stay active moving around in your home and on your property. I am writing this confined to a government compound overseas and I love me a good scotch. But I am doing my damnedest to wash/sanitize my hands regularly, and taking vitamins.
Do not become the liability for something unrelated to Covid-19. In that sense, maybe don't start up that P90x - you may hurt yourself. Follow up with people living alone. Check on your neighbors. Watch Stand Up comedy. Stay positive. For most Americans you have never experienced times of real distress, war, natural disaster, social upheaval, etc. Some have, and they are more resilient because of it. But check on yourself and your loved ones.
If our soldiers can spend a year at war and survive, the average American stay-at-home mom and office worker can get through this. If you are alone, losing your shit, and have no one to talk to. Get online and find an online therapist - many insurance companies cover this. There are Facebook groups out there too. Your sanity and those around you, can rapidly become a liability when it goes to shit.
Austerity. Endurance. Resiliency. Stick to those, and we will survive the zombies. Speaking of zombies, stock up some guns in your bunker. Fuck it, better safe than sorry.
If things get worse, and we have a lot going on in the world. Some education will go a long way. Years ago I spent a couple days learning urban survival under Tim MacWelch of Advanced Survival Training in Virginia. He has a lot of great resources and guidance at his blog: https://www.outdoorlife.com/tags/survival/
For a great book by one of my favorite authors, see if you can order before Amazon stops non essential deliveries, Emergency by Neil Strauss. You can find it here: https://www.amazon.com/Emergency-This-Book-Will-Save/dp/0060898771/
Caveat: This is a brief off the cuff write up. I will try to add to it if I have time.