I just started into "muh preps" just a bit over a year ago. It's earthquakes here in SoCal. Check into what is most likely to happen in your area and go for that.
3 days is for surviving the initial storm/power-outage/skinwalker invasion. To avoid the camps,
>>428234 has it right at 2 weeks minimum. It's what FEMA recommends for staying out of their camps. Katrina/Sandy have shown that the old 3-day recommendation is no longer any good since getting back to normal takes so much longer now.
For water....A gallon a day or a reliable water supply with treatment to equal that. The gallon a day is for everything; drinking, bathing, cooking etc. A pack of powdered water flavoring or powdered coffee is a good plan too so you can break up the monotony if shit stays in the fan for an extended amount of time.
Other anons above have had some really good tips too: hygiene for health and morale, gun if you can, weather appropriate clothing, pack of playing cards or books for morale. A way to cook foods. If you go cans, try for veggies or tuna that are in water to extend your water supply. Cans are also handy in that the food doesn't need to be heated, hot meals just tastes better which is good for morale. Yeah themes.
One of the aspects that I need to work on more is developing skills. You should check around the googlez and see what kind of /out/-sey classes are available in your area. I just got a new little camp stove (but the fuel had to be shipped separately) so I'll be cooking a meal with that on my patio soon. Whatever gear you buy, use it a couple of times so you know how it operates and any quirks it may have.
And, like... totes don't forget yur batonin' k-nif-ee
cont....
