I tweaked what the book said slightly but in the main I follow what it says; start with a white base (gets a more intense colour than starting with black) and then apply a thin yellow layer. Add a couple of layers of the thinned yellow paint and then start blending into orange (this works best by using thinned down layers as opposed to the feathering technique). One of my personal tweaks here is that the 'Eavy Metal team say to leave white recesses but I prefer to have yellow as the highlight rather than white so I paint the entire area and not just the raised ones. Then I start layering up with the orange, really thin to start but getting thicker. As the layers get thicker start mixing in some red until the mixture is just red. You should be blending the yellow into the orange and then the orange into the red. Over all that a really light dry-brushing with black. Another couple of tweaks I added here; the first is to mix in a touch of orange to the black so that it blends better with the flames (and I mean just a little bit. It's a hint not a colour change) and the 'Eavy Metal team also say to add little flecks of white but I'm not a huge fan of that so I leave it out.
The effect is thus (pre-tweaks):
I used an old Horror model that I'd done some skin colour tests on because, as you can see, he was holding fire.
This is after I worked out all of my kinks and tweaks:
This is the standard of my Horror Standard Bearer (I repainted the metal since, it's copper now instead of silver and I'm debating whether I can be bothered to repaint the gems in light of the new paints I've bought). As you can see I didn't leave that much white and the colours all blend into each other quite smoothly because of the really thin layers. I'd paint all of my models with really thin layers of paint but it would take way more time and effort than I have the patience for but when I have to blend that's my preferred technique. I used to feather my paint but I seem to have lost the ability to do that which is frustrating but this way produces better results anyway.
If I knew how to edit videos I'd make video tutorials but because I can't this will have to do. Anyway, adios, I've got things to do that unfortunately don't involve a paintbrush.