Fire Tutorial
I got the beginings of this effect from a tutorial on www.bluesfear.com. I've made some changes to it to get a different effect. The tutorial has 13 steps so it's 1 better than a 12 step program.
- Start with a new document. Personally, I've found that starting with a square document tends to work the best. A more vertical document tends to stretch the flames too much while a more horizontal document tends to repeat too much. My recommendation is to start with a square document and then crop to the final size if necessary. I tend to make it bigger on both dimensions so I can crop out some of the white if I want.

- The first thing to do is to set the document to white on black.

- Choose filter, render, clouds.


- Choose filter, render, difference clouds.


- Next, invert the image (image, adjustments, invert)

- Go into lighting effects (filter, render, lighting effects). You can play around with some of the options here to get a different look but I recommend starting with these settings untill you get an idea of what they do. The colours you use will affect the colour of the flames. I recommend a white light and an orange material colour. If you want more red, use a red or redder orange. If you don't use a white light then you won't have any white at the bottom of your flames.
Light Type: Omni
Intensity: 17
Gloss: 100
Material: 100
Exposure: 3
Ambiance: 25



- Use lighting effects again. Setting black as the material colour gives you black in the background of the flames. The white again, is needed to get white at the bottom of the flames.
Light Type: Omni
Intensity: 64
Gloss: 100
Material: 100
Exposure: 14
Ambiance: 13


- Use the accented edges filter (filter, brush strokes, accented edges). These settings are just a starting point. You can really affect the look of your flames by playing with these settings.
Edge width: 2
Edge brightness: 22
Smoothness: 15



- Apply a bit of guassian blur (filter, blur, gaussian blur). The radius will depend on how large your image is. For this image (300x300), I used a 5 pixel radius. The key is to look at the preview and make sure to just smooth out the edges a bit, not obliterate all details.



- Duplicate the layer (layer, duplicate layer). Set the new layer's blending mode to multiply.



- Merge the layers (layer, merge visible. Or, layer, flatten image).

- Use polar coordinates (filter, distort, polar coordinates), choose polar to rectangular.



- You will now have the flame effect but upside down. Flip vertical (edit, transform, flip vertical).


As I said above, this is meant to just be a starting point. Playing with colours, accented edges, and other blending modes can all change the look. I frequently duplicate the layer again and set it to overlay and then adjust the transparency to get a richer colour.