hey everybody thanks for all the comments
i like to read my mistakes too, every single time I start a new paint, i do a quick render in poser just to check out the lighting, as I know for photography classes at school, (Im not saying that is the only true) is always better to use 1 principal light, one fill light (about 1 third of the main light in the opossite direction) and 1 backlight this light has an special property, of giving that rim coming from the background, this is the most of the times very strong, this light helps to separate de character from the background, this is the basic ilumination for portraits in photography and film, thats why always like to put that extralight coming from behind,
thanks again for all the comments, as the title says is just an sketch, but i like to put my best always, so thanks for watching.
poser reference
with a little bit more of work