The book looks interesting I will get it.Thanks for the advice I will try it on paper although I dont have very still hand so I avoid drawing on paper but, hey, if I want to become some kind of artist it is necessary to draw on paper .

Pixelart is not the easiest medium to practice anatomy.. Better take pencil, some paper and a bunch of magazines with (semi-)naked girls (semi- because magazines with naked girls nowadays filled with silicone and botox and AIDS). Then trace, draw what you see and try to make figures out of head. And get a good book on anatomy, something like this one:

http://www.amazon.com/Drawing-Head-Figure-Perigee-Jack/dp/0399507914

If there is not one in the shop near you, pdf is floating around the Net.

Don't leave it. Drawing human figure is one of the most interesting things in art.