One technique I've read about is put a chunk of dry ice in the container, add the product, place the top on loosely until all the dry ice has vaporized and purged the container of air, then seal tightly.
This works very well. I've opened pails of dessicated rice and oats that have sat for three years in a cool basement and they were perfect. Exactly as you described, put a chunk of dry ice at the bottom of the container, fill over it, seal almost all of the cap/lid and let the co2 displace the air, then seal it up the rest of the way. Easy and very effective.
I'll start a list of skills.
Learn how to build a debris hut, snow hut, bow drill, small game snare, splint and sling. Learn how to strip bark or roots to make rope.
Learn how to stitch cuts and gashes. Practice with your dinner before you marinade it (srs). Learn what first aid to give in various circumstances and how to give CPR. Learn how to smoke and salt meat.
Learn the most common edible wild foods in your area. Learn the migratory patterns of edible animals around you. Learn the prints of common animals and learn how to spot signs of recent activity wherever you are.
Learn the properties of whatever wild medicinal herbs are around you. Always be growing plants, even if it's indoors in the off season. Life begets life.
Learn how to leave signals that betray others' presence in your absence.
Learn how to shoot moving targets at a variety of speeds, heights, and distances. Learn to shoot accurately while running. Learn how to strip, clean, and reassemble a handgun. Learn how to counter a gun in your face.
Study SWAT and military combat movements until you can play them out in your mind and visualize ways to counter or preempt them.
Practice analyzing buildings for entry/exit points, cover points, escape routes, etc. Learn how to put out various types of fires and how to escape a burning room.
Learn how to drive a stick. Learn how to drive offensively, minimize injury and damage in a car crash, and how to hotwire a few common cars. Know the shortest routes to important points in your area regardless of traffic patterns or right of ways. Know your evacuation routes and how to get to them from places you commonly stay. Know your AM and shortwave stations.
Practice being able to point to the four cardinal directions without thinking about it wherever you are. Learn how to read a map and orienteer with a compass. Practice guessing the time to within a few minutes from the light in the sky. Practice being able to point in the direction of major geographic and manmade features from wherever you are like ocean, rivers, crops, power plants, airports, highways, rail tracks, etc. Learn how to predict the weather.