From TDN

First we need some fire!

Particle systems can be rendered very simple to achieve a natural effect. Browse real explosions and fire burning effects on you tube, freeze frame them... Then draw them by hand. Draw smoke coming out of a chimney. Look at DaVinci's studies of explosions and deluges.

The final Particle should be illustrated as if was a fractal pattern. Self similar elements will trick the eye into thinking that there are more emitters than are scripted. Actual photographs may be layered on top of the original idea.

Now we can start coding particle systems.

Is it hot? Maybe some negative "constantAcceleration" will suck the particles back up. The hotter, the lower the "gravityCoefficient", try -4 for some smoke.

If it is really hot in the ParticleEmitterData: "'ejectionVelocity'" will be high, and it will go UP! thetaMin=1; thetaMax=20; The particle data will spin more too. - "spinRandomMin" / Max.

Can the wind take it? Here it gets a little tricky with the "dragCoefficient". A particle going from hot to cold fast will have a high drag. This may not be the case if the particle resizes large quickly, then stays the same size, with an ejection velocity of under 15.

Times[0]=0.1;Times[1]=0.2;Times[2]=1;

with sizes[0]=3; sized[1]=13; sizes[2]=24; - steps 3 to 13 takes a bit

                                                                    - steps 13 to 24 takes a while

now match up the particle data windCoefficient to the effect.

Multiple layered particles usually have a smoke, spark and fire emitter.