I took a look at the tutorial posted by Spectre,
Have to say that would be the best way to make realistic fire!
If you want to, try this --
once you have your fire base done, copy it to another layer -- then liquify a little. Now go back to the base fire and copy to another new layer, this time liquifying a little more -- repeat this until you get about ten layers that have been liquified more and more.
now save the file as a *.psd
Open the file in image ready, then turning on the base fire (leaving the other fire layer off) and any bg's/fg's on.
Ad a new frame, this time turn off the base fire and turn on the first fire layer (the slightly liquified one) keeping the other bg's/fg's on.
keep doing this until you have 10 or 11 frames (all with different fire layers on), set your timing down and save optimezed as "*.gif"
that's about as simple as I can make it for ya'!
Good luck! 8}
