it's getting pretty late here and I'll have to go to bed soon, so I'll just list a few quick things:
1. The proportions are off. Try to understand the shape of a head and construct it to ensure you place everything in the right position. Here is a quick tutorial http://foervraengd.deviantart.com/art/MANGA-to-REALISTIC-PART-TWO-215600120 Understanding this method will also make it easier to draw things in perspective and not just from the front.
2. If you are trying to draw realistically, you will need to get a lot more details in there. Hairs aren't just a few lines with a common general direction, Noses aren't as catlike as they are in your picture, etc. In general you are simpliffying too many things while also slightly distorting them. Doing this right requires either looking very very closely at what you are trying to draw or a very good understanding of anatomy (preferably both) I'd point to Gottfried Bamme's "Die Gestalt des Menschen" (roughly translates to: the human form) but as I said before it is only available in german and not for everyone… Maybe take a look at Betty Edward's "Drawing on the right side of the brain. In this book you'll find a lot of good tips for understanding the "right way to see" things with all the details they contain.
3. Learning all of this isn't easy. It takes tons of practice. If you want to get to an actually realistic look, you'll have to practice and do hundrets upon hundrets of drawings. Not neccessarily of entire faces, but individual features like eyes, noses, mouths, etc. If you are trying to improve, try to do so step by step by focusing on one aspect before you try everything at once. It is much easier to see your own mistakes this way and improve.
4. Speaking of improvement. I'd suggest that you do not shade the pictures until you have an understanding of the proportions. Shading makes pictures a lot better (most of the time) but it does so by disguising mistakes you made which in turn makes it harder to find them and improve.
In general I'd practice the basics (anatomy, proportions) if I were you. I hope this wasn't too blunt and if so, then please forgive me, but as I said in the beginning I am somewhat tired right now and need to go to bed. Take care and keep going!