Jonathan Lampel gives an extensive overview of fire and smoke in Blender in this two-part video tutorial.
Simulating and rendering convincing fire in Blender can be tricky business. But thanks to last year's GSOC project by Miika H., we can now easily create good looking flames.
In part 1, I go through all of the smoke sim settings that pertain to fire so that you can understand what to tweak and why:
In part 2, I show you how to make a nice material that can create both realistic and stylized fire by adjusting a few simple settings. I also cover a compositing setup that transforms our bland render into an eye catching final image:
I hope this helps, and I would love to see what you can come up with!