So I really do not like the Clamp style all that much... but I enjoyed Code Geass for the story. It's too pointy for me, and the anatomy is not as accurate as it could be. So this was a challenge. Especially that chin. Pointy chins are just so hard for me to draw, because I just want to smooth them out. The nose was difficult too.
So it's been awhile since I watched all of Code Geass... but I'd say Zandra would be most likely be closest to a mix between Kallen, Cornelia, and Suzaku, maybe? It's hard to tell, really. But as for how she looks, I referenced Kallen and Shirley.
I really like the story and everything in Detective Conan a lot, but the art style isn't my favorite. The noses have always looked so odd to me. But I like that Gosho Aoyama's able to make so many characters and make them all look pretty different.
As for the character comparisons... I would probably compare her to a mix between Haibara, Sato, and maybe a tiny bit of Kir or Ran? And I referenced Ran and Sonoko for how she looks. During her time that she was just becoming close friends with Amber, I would definitely throw in some Sonoko for her personality type.