Besides protection from Imminent physical danger the most important necessities are water, food and shelter; in that order. Learning how to find and prepare these things is job one. Water can be found probably easiest of all; for now anyway. Food is essential for energy and staying focused. Calories are needed to maintain energy. Two meals a day will be a luxury. Learn to consume less but more of what will sustain you and is essential for health. If you have medical issues, this fact becomes even more crucial.
Our current dependence on processed and distributed food is based on farms, plants and distribution systems. All of these run on fuel and to a larger extent electricity. Those of us who have experienced prolonged outages of electricity understand that most everything stops. The pumps that pump gasoline run on electricity.
Something to think about; how much of the plant and animal life is there to sustain those who seek it. The point of all of this is that we are relying on a very fragile system; as do all the industrialized countries of the world.