A good start. I Can't model humans to save myself, but I can draw them. Some elements you might what to look at however, the corners of the mouth should be directly in line with the pupils of the eyes. and you might want to look at the profile a little as it seems flat to me. This is of course assuming you're trying to make a realistic human head and not a characture, in which case you can feel free to tell me to shut-up and get back in my box. :-) But really this is much better than I can do with modeling people, so keep at it. Pagrin :-)

A good artwork takes time.

I think there are many things you may want to look at when modeling. From a mesh perspective, your head models seem to be constructed improperly. I have noticed that you post the same head with many color variations and props that are not changing or improving. From a modeling perpective, i would recomend you go to www.3dtotal.com and look at some of the awesome tutorials online to teach you how to model correctly. As i look back through your gallery, you have posted "nearly" the same model every week with no improvment. To improve, you need to start changing some things as this the way you will learn wat works and does not work. keep at it but for goodness sake, actually do something to the model so that people will fell the need to critique your progress. I think you are trying and thats good, however, i haven't seen your model progress.