Two important tasks.
1. Stock up on food.
2. Learn what's edible outside your door.
STOCK UP: This depends on your space and budget. If you have a lot of both, you are blessed.
Thrive Life is the best tasting long term food I have found, and it's cheaper than most: https://www.thrivelife.com/shop. Many of it's products last 30 years. You don't have to worry about expiration dates for a long time.
If you are short on space and money, just spend $10 a week extra on canned food that you like to eat. By the end of the year, you will have quite a pile. Store it under a bed or some other out of the way place. Label it with the year. After a few years, pull it out and trade it with new cans. Most canned food has an expiration date. It doesn't spoil after the date, but the quality deteriorates considerably.
LEARN: Someone can steal your food. They can't steal your knowledge of how to not to starve. I live by the Oregon coast. The edible plants here are probably not what you have outside your door. Find a book or website and LEARN all you can.
Here are my favorite sites: http://wildfoodsandmedicines.com/
Some info just tells you what berries are good to eat. I am interested in whether I can eat the leaves. The berries are more tasty, but the leaves, even if they taste nasty, are present all year long and can keep me alive.