I'm trying to learn the same things for my own characters, sometimes poses and expressions help develop the character.
I like to think back to a great character design like Porky Pig and think about what makes that last, and I guess if all else fails I really need to start watching real live people to see what makes them unique
It can't all be hair and eyes that define a person!
Well, I was always told, the key to originality and uniqueness is to add a piece of yourself into something you make, then add on until you're satisfied. That's exactly what I do, but sometimes it's kinda complicated, but music and what surrounds me everyday is what I use for inspiration. Once again, you are right, Hair and eyes can't define a person, and those who think that, usually end up as "Mary-Sues". It is DEFIANTLY a necessity in an artist to be original.
By the way, I think she would make a great partner with the Scorpion Lady instead of the nurse. Especially since Egypt is a desert region with scorpions and the relation between The Mummy and the Scorpion King movie.