I started by trying to separate this girl from the original background.
This is what I ended up with.
Not too bad, but not great.
I created a brush to draw hair strands.
I wanted it to go from thick to thin and I wanted to use both foreground and background colors and jitter back and forth between the two to make the strands look like they had texture.
I grabbed the freehand pen tool
And quickly started drawing paths.
I went to the paths pallet and went to the "stroke path" selection.
And applied these settings.
(GET A PEN TABLET FOLKS!!)
Change the colors every now and then adding darks and highlights.
Do a few paths of one color combo, then do some with a different foreground and background color combo.
Continue until you get a look that you like.
Here is what the brush stroke looks like if I make it really big and exaggerate it to show you how it works.