Now duplicate the ‘model’ layer, naming the new layer ‘model glow’. Go to Filter > Stylize > Glowing Edges. Set the edge width to 6, the edge brightness to 7, and the softness to 7.
Still in the ‘model glow’ layer, delete the rest of the body, leaving only the arm. This will be the highlights of the fire. Also, change the blending mode to Screen.
Add a new layer, naming it ‘model mask’, then select Filter > Render > Clouds, setting black and white as the foreground and background colours, respectively. Go to the Paths palette and load the path you created in step 2. With the selection loaded, go to Layer > Layer Mask > Reveal Selection.