Her hair gave me a lot of trouble because I always have trouble with the shape of hair. Her eyebrows were kind of tricky too, since she's blonde and also light-skinned so it was hard to make them stand out, plus the whole super-long aspect threw me off for a while. Finally, I had to hold back on some dramatic lighting ideas, because her eyes looked creepy whenever they were in shadow, and I have a tendency to put faces into deep shadow for emotional effect.
So it was just a matter of starting out the concept a little too crazy and having to tone it down a bunch of times, which was frustrating and somewhat momentum-killing for me. But there was also quite a bit to learn from the experience, as usual