Well... the green effects on the shadows were painted green-gray since the beigining and once I finished everything what I considered to paint I applied a color correct and hue/saturation as well (and as I always do for doing the final corrections -levels, exposure, gamma and curves too-) There s where the general corrections comes. The decomposition of light is pretty simple, you can practice with that: take a Ctrl+C from the whole thing, paste in a new layer, select one of the three channels (green, blue or red) and also with a general selection just move it around or apply a transform and make it bigger or smaller selecting with Alt+leftClic the center where you want the focus of the whole image.And the particles are just round brush and a biig scatter. Some dots bigger some dots smaller and then apply a gaussian blur where you want to make it look closer or farther.I hope this help you... if not, feel free to ask again and if doesn t work at all I can make a little tutorial for this stuff, it s actually pretty simple