The Basics...
Know the FIRE TRIANGLE: HEAT-FUEL-OXYGEN (i.e.- Flame-Wood-Air) With these 3 things you will have FIRE. However, if only 1 of these 3 things are missing you will get nothing but failed attempts and maybe a little smoke.
Location & Materials...
When picking the location for your fire just use common sense. Will my fire burn anything down? Is the wind going to blow out my only match? Did I build a fire pit with wet rocks that are going to explode, when the heat turns the water inside the rocks to steam, injuring or killing everyone? Often when people are making fires in the wilderness, the best way to make a fire pit is to dig a cross shaped (plus sign shaped) trench with the fuel in the center. The trenches, a few inches deep, will allow air to reach the fire. You may find that a free standing fire is perfectly sufficient.
Dry or extremely flammable materials are essential. If you are without flammable materials of your own then you will need to search the surrounding area for tinder.
Tinder is any easily lit, flammable material for starting a fire. Shavings from a stick make great tinder.You can also use leaves, small twigs less than 1/4" in diameter or tall dry grassy matter. When searching for tinder the key idea is within the fire triangle. The tinder will be your fuel and the oxygen is in the air. The trick is getting your heat source to heat your fuel (tinder) to combustion.
Understanding heat energy absorption and dissipation is vital to starting a fire. Do not try to use a match or sparks to light a log. The log will absorb the heat energy applied, dissipate the heat energy, and ultimately not light the log on fire. Therefore, you must find tinder. Tinder will absorb and dissipate the heat energy differently than a log. With tinder, the rate of heat absorption will more likely be greater than the rate of dissipation. This allows the heat energy to build up igniting the tinder.
Once the tinder is lit, you will have a greater heat source. With a greater heat source you also have a greater amount of heat energy. At which point you can begin to build up your fire with slightly larger sticks. Once the sticks are lit then you can put on larger branches and finally logs. Be sure not to jump ahead too quickly. Being too aggressive may cause your heat energy to be absorbed too quickly, putting your fire out.
If all you have is wet tinder then remember one simple rule. "If it's hot enough, it will burn." Most tinder can be dried using your body heat.
If you can get the tinder to light then you have a really good chance that everything else will too. Practice makes perfect!
Lighting The Fire...
There are many ways to light a fire. The simplest, and possibly the most well known, is by the use of a lighter or matches. If either of these are not available then one of the following methods may be used.
Flint (Can be bought and sometimes found in certain areas.)
Magnesium Fire Starter (Sold at Wal-mart)
Magnifying Glass-->Magnifying Glass Fire
Forming ice to work like a magnifying glass. (very complicated)-->Ice Lens
Using a 9v battery and steel wool-->9v and Steel Wool
A modified cell phone battery may be used-->Cell Batt. To Start Fire
Bow Drill-->Bow Drill Fire
Hand Drill-->Hand Drill Fire
Bottle Of Water-->Bottled Water Fire