The fire in me...

Invert the color of the main layer

Highlight the edges using Filter > Stylized > Find Edges.

Add several layers of fire to cover the whole image and position them effectively

Use liquify to blend the fires

A layer of fire is set to Vivid Light to color the white outlines...

Modify the Hue/Saturation and Brightness/Contrast

Credit from http://psd.tutsplus.com/tutorials/photo-effects-tutorials/flaming-photo-manipulation/