The idea is very good - a bit poorly executed, but I love the nose part :)
I think you'd benefit from going away from the spikey hair and start thinking out some kind of hairstyle: http://www.youtube.com/watch?v=pm1nzZa2RZQ That video won't help for male hairstyles but you'd be learning a lot from it :)

Could you give me the hex code for the green color you've used as your main color? I wish to see if I can help you pick a brown color that would fit better.
If you wish to; pm me the .psd and I'll fiddle around with it