I have to echo Pocky-Yoshi's criticisms. Your color choice is okay (except for the first design, it almost looks as if you didn't color anything at all), but you need to do some work on adding in detail. Your Viola-style designs aren't too bad in this regard. That last middle-eastern one is actually pretty good and the second black-and-purple-colored one is alright. It just needs a little touching up, like expanding the purple sticker on the midsection to max size to it covers all 360 degrees on the torso. Everything else looks very plain and uninspired.
I also want to address your positioning of special equipment. I don't get why the hat on your first design floats several inches above the head. Same deal with Snow White's ribbon, which is also skewed at a weird angle. Then there's the apple at her feet, which I can imagine just looks strange during in-game animations.
As far as part choice goes, I see some things I like, here. The Cropped Jacket and Noble's Dress as seen in the first design work well together. I also like the Corset and frilly shirt-bra thing combo seen on Snow White.
Finally, some advice:
1) Go into creation mode and run every tip and trick mentioned in here:
http://8wayrun.com/threads/dampierre-and-cos-cas-tips-and-tricks-compendium-curio.12735/
A good bit of them are in the spoilers on the first page, but it's been a while since the thread's been updated.
2) Look at other peoples' CaS, zero in on details that you notice, and figure out how they did them. Pay attention to things like part choice, coloring/stickerwork/pattern usage, and special equipment use. Challenge/contest threads are a good place to start. Those can be found in the Link Thread that Pocky-Yoshi mentioned. After that, go into the personal threads of people whose contest entries you liked.
That's how I learned CaS, at least. You do those two things and I guarantee you will see at least a 50% increase in your CaS ability or your money back.