First and foremost, I hate hair and it hates me. I cannot tell you how many different mediums I've tried and I have yet to get the lighting down when it comes to hair. If you have ANY pointers for shading hair or locating a lighting source, I'd be more than grateful to review them! Please do ignore the ear. I erased it after noticing just how deformed it really looks. The neck isn't complete either. I'd also appreciate it if anyone can look over the shading or bring to my attention any flaws you may have noticed.
I'm just throwing this bit of an image out there to show the shading around the eyes. I'm not too sure if it makes a difference and if it does, for the better or worse? In short, C+C, please! (Minor detail, I'm new to this lovely community! 
)
Advice for rendering hair:
* Start out with a dark fill (either the darkest hair shade, or the 2nd darkest hair shade.)
This will help you see the shading/lighting more clearly (and it tends to just plain produce cool-looking results
* Look at the way hair is rendered in anime. Block it out like that.
* if more shading is needed, you just kind of push the ends out as you reduce the brightness of the line -- you need to have a sense of how the hair is going to bunch up in 3d.
* If you don't know how to light the hair, this means you haven't firmly established it as a 3d object in your mind. This means you probably haven't drawn a mesh for your head -- this is a vital aid! (this effectively requires you to fix the ear.)
This should be done BEFORE blocking out, on a separate layer.
Here is a quick (BSed) edit. it is not
remotely correct; however, it may give you some idea what I mean.
Checking out jaeden's work might help you too... and fur, as in
http://pixeljoint.com/pixelart/5884.htm or
http://pixeljoint.com/pixelart/5647.htm. Don't listen too hard to me though
I tend to BS hair based on my understanding of how to render fur, as you can see in the previous two links
In the future though, my #1 recommendation -- do the entire picture at once, rather than adding parts afterwards. This is one reason you've drawn rather huge hair (vertically on the picture) and probably also caused the defective ear. Being methodical like this can save you from vast amounts of silly mistakes.
