Was studying this facial expression to use in a panel, and I figured I'd clean up the sketch and post it, before deleting the layer.
When I have to do a new facial expression, sometimes I sketch it right on the page a bunch of times, from various angles, until i have it down.馃
Rough pencils -> Pencils -> Inks.
In the inks I fixed her baby face, which wasn't on-model.
Also, often the rough pencils are a ball with a cross, not always this detailed.
Not revolutionary advice, but it's true: Think of hair in chunks, rather than singular hair strands, then shadow accordingly.
After that you can decide how much individual detail each hair should get within the chunk, based on the style and overall image. Quick example: