Looks good, man. However, you'd be far better served to do humans if you wanna get better.
I know it sounds odd, but everyone does aliens in modelling. This is your first try, and I'm not trying to be a dick or anything, so please forgive me if I sound like it! I guess I can't help but be a dick, if you look at my name!
Just giving some information, as someone who's done this kind of stuff before. Your first try looks really good, though!