Firstly, we should act in the way, which should be good if everybody will act in the same way.
Really? I'd generally prefer to act in the ways that will be most successful given my predictions of other people's actual behavior. The question isn't "how should a population of Hofstadterian superrationalists, who will independently figure out the best way to cooperatively act, prepare?" It's "how should we prepare?", and I infer you really mean "how do you intend to act and how do you recommend I act?".
I don't currently see a need to prepare any differently than normal life: I keep about a week's very comfortable supplies (which is ~3 weeks rationed non-water supplies) for my family, and a somewhat extensive first-aid kit. I recommend the same to you (and anyone else who asks). If you're particularly cautious or altruistic, you can multiply by the number of neighbors you want to care for in a disaster. I also recommend a "go bag" with some portable supplies and money so you can evacuate very rapidly if necessary (and pre-commit to "in an emergency evacuation, we're not taking anything we can't carry - we set any pets free outside, we lock the doors and GO"). It's a very personal decision whether you want weapons available and the required training to be safe and effective with them.
In most big cities, any more preparation than that is dominated by significant lifestyle change and moving somewhere less populated. A cabin or vacation home you can pre-evacuate to if it looks MUCH worse than today would be ideal. Any extended collapse (say, no services for 4+ weeks) is just going to kill most people who didn't get out.
For my current understanding of this outbreak, the normal prevention mechanisms (wash hands a lot, don't touch your face, etc.) are sufficient as well. If it gets noticeably worse, I'll add gloves and drive to work rather than using public transit for awhile.
I've done a very rough fermi estimate (I even pull some numbers out of my ass), according to which I don't need to worry. The probability of me dying due to ncov 2019 is
In total I get approximately 6 micromort, which is really low - on average I probably get about 25 micromort per day according to wikipedia. (EDIT: 25 micromort per day is a huge overestimate for my age of 25 - actually I have about 1.34 all causes micromort per day)
The death percentage should perhaps be higher than that 3% actually, since it takes time for someone to be killed by the illness, and most of the people infected have not been infected long enough to die of it.
There's the opposite effect: the early diagnosed cases tend to concentrate on the more obviously serious ones (more likely to die).
Where did you get the idea that the number of infected people doubles every two days? https://forum.effectivealtruism.org/posts/g2F5BBfhTNESR5PJJ/concerning-the-recent-wuhan-coronavirus-outbreak suggests that each person might infect 2.6 people on average and the incubation time is relatively long.
https://en.wikipedia.org/wiki/Timeline_of_the_2019%E2%80%9320_Wuhan_coronavirus_outbreak
23.01 - 830
24.01- 1287
25.01- 1,975
26.01 - 2,744
27.01 - 4,515
It seems like you only pick the time-frame where there was international attention on the issue. I would expect that this attention raised the discovery rate.
I pick just recent numbers, but exponential two-day doubling trend in infections and deaths is visible in the wiki-table from 16 January, or for around 5-6 doublings. Total growth for 12 days is around 100 times.
It has been doubling in this time frame, but that's because of its unique circumstances. Many other illnesses have had a similar rise when they first appear, but illnesses tend to have their peak and then cycle down. Perhaps this may change, but the data does not indicate that yet.
It is also good to invest in improving ones’ immune system by health food, vitamins, light therapy, as it is our best protection of the virus. Evacuation into a cold county house would weaken the immune system.
How much can one "improve" one's immune system by these methods in a short time? Is there any data to back this up?
In general agree with the rest. In worst-case scenario ability to self-isolate for a while ("bug in" in prepper lingo) seems worthwhile.
One estimation is based on the straight extrapolation of the exponential growth of the infected people number, which doubles every two days. This implies that the whole population of Earth will be ill in March. Another view takes into account that many mild cases are not included in the stat, so lethality is small and probably not everybody will be ill at all. We just don't know yet.
Both of these estimates wildly exaggerate the risk. Why in the world would we expect exponential growth to continue? Rather than "probably not everybody will be ill," our baseline should be "a few people will be ill," because that's what has been the case with almost all other epidemics.
If you don't live in China and are not planning to go to China soon, the appropriate course of action is to do nothing.
There are different estimates of the possible severity of the current coronavirus outbreak. One estimation is based on the straight extrapolation of the exponential growth of the infected people number, which doubles every two days. This implies that the whole population of Earth will be ill in March. Another view takes into account that many mild cases are not included in the stat, so lethality is small and probably not everybody will be ill at all. We just don't know yet.
How we should act personally in this situation?
Firstly, we should act in the way, which should be good if everybody will act in the same way. For example, panic evacuation is not good, as if everybody starts running away, this will only increase the dissemination of the virus. Thus the best approach is home self-isolation, lowering of the outside contacts, wearing protecting gear (mask, goggles, gloves), hand cleaning. UV-lamps may help in the disinfection of things.
It is also good to invest in improving ones’ immune system by health food, vitamins, light therapy, as it is our best protection of the virus. Evacuation into a cold county house would weaken the immune system.
It is probably reasonable to collect one month supply of food, water, and other essentials, as the possible pandemic may affect food manufacturing, and also wholesale buying minimise future need to go outside.