Very nice outcome =o
But try to make darker tones using "colorize" mode and cranking down the Lightness slider...
Anyway, a quick tut explaining.
Usually, to color sprites, people usually just fill the pixels with their desired color using the bucket tool.However, that just doesnt work with artworks, because there are just too many pixels too fill 1 by 1 and some colors conflict with each other.But theres another way to color both sprites and art.
You ALSO, fill each part in order to "mark" where to color, otherwise the program wouldnt know where you want to change de stuff. Keep in mind, different parts, different layers.
Proceed then to CTRL+U/CTRL+B while having one part selected, again CTRL+Left Click on the thumbnail of the corresponding "marker".Thats it, simple...FOR AWHILE.
For artworks, you do the same thing.
This time, you use the pen tool to accurately mark.Polygonal lasso is fine too, but lacks some precision.
Its a harder than a sprites for 1 reason, you have to fill the parts manually, since the Bucket wont help you this time.
Thats pretty much it, If you still cant get to color the rights parts, I recommend download one of the templates provided in the first page