Starting a Fire
The importance of being able to build a fire in any situation or environment can't be overemphasized. Besides providing essential warmth and light, a fire is necessary to cook food and purify water and it will keep dangerous animals and insect pests away. It can also be used for signaling, drying clothes and making tools. Always carry a magnifying glass and butane lighter and keep your eyes open for dried moss and milkweed or cattail fuzz to use as tinder.
Building a Shelter
In a wilderness environment, exposure is the number one cause of premature death. That's why knowing how to start a fire and build a shelter are the most important skills you can have. A good shelter can protect you from extreme temperatures, windchill, getting wet, getting too much sun and dangerous animals or insects. Your clothes are your first layer of protection from the elements. Stuff them with dry leaves and grasses to stay warm while you build a proper shelter.
Signaling for Help
Getting the attention of potential rescuers that are out of your reach can bring a quick and happy end to a survival crisis. You can attract attention with a fire or flashlight at night and smoke signals, the sun's reflection off a mirror or bright colored markers during the day. A loud whistle or the discharge from a gun is also effective and a personal locator beacon is even better. Anything that's done in threes is considered a distress signal. This includes three blows on a whistle, three flashes from your mirror, three puffs of smoke from your fire or three markers in the shape of a triangle.
Getting Food and Water
You can only carry so much when you're traveling through the wilderness but a crisis can deplete your supplies. Once you realize it will take longer to get back to civilization than you expected, start rationing your supplies. Fill your water bottle at every opportunity and drink it dry before you do. Always boil, filter or chemically treat the water before drinking it. Transpiration from plants, morning dew on a cloth, a solar still in the desert or blue ice on the ocean, are all sources of potable water. If you learn how to build traps and snares, identify edible plants and locate edible insects, you'll always have something to eat.
Administering First Aid
Always take a first aid kit and space blanket when you venture off the beaten path. You can use them to keep warm and treat minor cuts, bites and burns. If your injuries are more serious, the ability to stay calm and think clearly is critical. Learning CPR and other EMT skills will help. If you run out of supplies, the sap from a fir or spruce tree makes a good antiseptic and many plants have medicinal properties. Learn what they are.