Chuck the mascara now that they have that in.
Practice the 3 rule: one to use now, second in case you loose it, and third a back up when you run out of it.
What have you worn in the last week?
How similar is everything? I buy things for separate look. I have purples for a smokey look, and greens and golds for a different look, and probably will get one more darker eyeshadow to put on eyeliner, but then thats it.
DO NOT BUY ANYTHING ELSE UNTIL YOU RECTIFY THIS! and think about it this way, the more you throw away, the more space you'll have for a new look, but then control yourself once you have the space.
I would first chuck the stuff you haven't touched in the past 6 months. Come on girl!
Then go in the past couple of months,
then the items you use rarely.
Then catagorize the rest into different looks for different aspects of your lifestyle ie. work, casual, formal, semi formal, and the more you overlap the better.