to the FSM forum first off.
That's a classic that you found. Always wish I bought one when I had the chance. In any case, I don't think you could do a single colour to have a good representation of fire, as fire in real life has many different shades of yellow and orange.
I'd start off with a dark yellow basecoat, then a dark orange/light brown wash, very thin. After that, a fairly heavy drybrush of the base yellow followed by another wash, this one with a brighter orange, again very thin. After that, a drybrush of a lighter shade of the base, followed by a very light dry brush with white. You can take this technique of layering very far, it all depends on how well you want the fire to be represented. if you wished to, you could only do a basecoat, a wash, and a drybrush, but each of those at least once.
Good luck