On a more specific note, the most glaring problem is the shape of her face. The lower portion of her nose, where the nostrils would be, is too big. The area between the tip of your nose and the top of your lips is generally not much wider than two fingers, but Iku here could fit three or four.
Remember that noses point downward, not upward, unless you're going for a pig-like character. Which is, sadly, what Iku looks like with that nose.
I won't be able to point out all of the problems with this picture, but you should have been able to catch some mistakes simply by comparing it to a quick Google image search on "profile." Do you use references?
It may also help you to compare the heights of the features side-by-side with your own front-view drawings.