Yosh64: I don't mean to be an ass, but I had a look at those links and I found them to be absolutely horrible. Polykarbon has great tutorials and was a good idea to link to, the rest on the other hand all had fundamental flaws in them. A lot of the tips given do have the correct information, but the artists writing the tutorials don't seem to know how to use them themselves. I checked out the anatomy and face tutorials and the examples given were very wrong and could easily give the wrong idea.
I would stick to Polykarbon in this case, I've checked there a few times myself in the past.
Sohashu: If I am to point out a few obvious faults, the head is too flat. Make it longer but remember to keep the eyes in the center as they are now. The eyes could use some dark lines at the top to indicate eyelashes and depth and the iris of the eye looks like it's separated in two bits the way you're using the gray at the bottom and black on top. Eyebrows are a nice detail too
There definitely is a lightsource in anime, just like in most art. Try to move the lightsource to the top rather than head on as it usually gets missunderstood as pillowshading. Lastly, and this is just my personal oppinion, it's a lot more interesting to do a 2/3s portrait. (head looking slightly left or right).
Hope it helps.
