Creating smoke skull: I took this image http://www.flickr.com/photos/quinet/125138966/, cut the skull out, created new layer and draw smoke on it. Made the backgroun black so smoke is more visable.
step 2 of 5
Than using soft eraser and smudge tool I've created the shape of skull.
step 3 of 5
Using eraser 25%, smudge tool and burn tool I've created eyes, nose and teeth shapes.
step 4 of 5
Than just removed background and skull image and moved the skull to the main picture.
step 5 of 5
Created layer mask and with black brush I've "fitted" the skull to the fire smoke.
It's my first SBS, not sure how to make it :) I also deleted my original smoke skull I've created first and had to made a quick SBS for admin's request. So they might look a little bit different. But the technique of creating was the same :) And of course took much more time to do it.