The faces look off, but the anatomy is pretty good.
Keep drawing, mate, you have potential.
It looks like the sketch was done on paper, but what software&tablet are you using for lineart and colors? The lines are kinda shaky, you could use a better stabilizer. >inb4 'I use GIMP'
try krita, it's great, if a bit tough to first get a hang of. Or sai, if you want something simple and lightweight, although it's pretty limited.