I'll add highlights and shafts of light coming from the sky, It's just an sketch, and I need to dithering all the background before that and know how to do the leaves for start to paint the tree
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Edit:
My sketchs are REALLY bads, do not take them too seriously, you can see it there:
Before:http://i1157.photobucket.com/albums/p584/Pukahuna/Lava3_zps97dc57df.png
After:http://i1157.photobucket.com/albums/p584/Pukahuna/final_zps212e13dd.gif