If you are camping, or are lost in the woods, the most important thing to your survival is warmth. I don't know if you have ever done wilderness survival training with out a sleeping bag or tent, but let me tell you, without a fire mine was cold. I wasn't allowed to make a fire, but if I ever need to I can, and you need to be able to make one also or you could die.
Disclaimer: I will never say that fire is a bad thing. It saves lives both from cold and boredom when camping, but if left unattended or used inappropriately, it can be dangerous and unpredictable. Don't be stupid.
Step 1: Tools
You always need the right tools, whether your camping, going on a hike, or just away from safety. If you are in any of these places with out at least some of the following, only you can be blamed for your death.
A knife, good sized and strong
Flint and steel(Sorry, no picture),
9v battery and steel wool,
The matches should include both strike anywhere and light when wet, you could need either.
I suggest you have all of these, they are light weight and can fit in your pocket.
Step 2: Gather wood
This is very important, the wrong type of wood could cause your fire to go out, and if your in the woods without a car or you're lost, it could mean death. Don't listen to what anyone says, size matters. You want a few big logs, 2 or 3, but not to many. It takes a long time to get big logs going, and a lot of fire. But don't get only small sticks. They will light, but not for long. You want a big log (>3 in. thick) per 5 medium sticks (1-2 in. thick) and about 20 or more small sticks (<1 in. thick).