In many instances fire will be the most critical need, even before food and water. Shelter is easy to come by. Dig a foxhole, find a hollow tree, etc. Some shelters are better than others in some instances, but here we will talk about fire.
The only real survival fire making technique is rubbing two sticks together in some form or other. But unless you practice regularly and can find some dry wood, better be prepared. Carry fire making tools ALWAYS.
Good tinder and edible inner bark.
Because of it’s oil, the loose bark of the yellow or other birch makes good tinder even when wet. It burns hot and long. The inner bark is edible and tastes like wintergreen. Most wintergreen flavoring comes from black birch.
If you are having trouble with a flint and steel outfit, you should know how it works. Steel has carbon in it. Yeah, like charcoal or coal. Iron also oxidizes, but not self sustaining. Does your steel have enough carbon in it? Dixie Gun Works at dixiegun.com sells a good steel just for that purpose. The idea is to scrape minute particles of steel mixed with lots of air using enough friction to ignite them. Remember, a quick scrape gets a shower of sparks. A quick hit may or may not get a couple of sparks. Learn to knap and keep your flint sharp. Once you’ve got lots of sparks, they may not light anything unless it’s very dry. It’s not a metal match. In the Eastern US especially, you will need char cloth. Poke a pinhole in a shoe polish can and bake some cotton t shirt material in it on the barbecue. Don’t smoke up the wife’s oven or you will have an emergency at home.
To make char cloth for flint and steel, put old t shirt or other pure cotton cloth in a can and put a small hole in the lid. Cook it till it quits smoking and let it cool before opening the can. Don’t block the hole with the cloth or the lid will blow off.
Ferro rods can be bought for those wanting to make their own fire steel. One place is http://www.usaknifemaker.com/.
Don’t forget, a pocket magnifier can be used to start fires if the sun is bright. Cloth or paper is easier to ignite than loose tinder until you get good at it. Put the cloth or paper over your tinder and tilt the glass toward the sun. Move the glass closer or farther away until it focuses the light in the smallest spot and hold it there until it burns a hole and hopefully starts the tinder underneath.