The key for me is making fire without any pre-prepared stuff. Sort of like Tom Hanks on the island in Castaway. It's one of those things that you need to practice a bit; if you never practice, you'll never know how to do it if you really need it.
A couple of sites on primitive fire-building...
Primitive Outdoor Skills
Primitive Fire Starting
Wilderness Survival: Firecraft - How to Light a Fire
And the one I think is best (lots of info besides firemaking)
Primitive Technology, Traditional Skills and Hand-Made Tools