For her shirt, we decided that it should look like its made from silk and have a oriental design on the back.
I had to edit my post a little bit, since some people were asking me about the design on the shirt :D
I did paint the design all free hand. Its the same design that I used on the fan on Mai from King of Fighters ( http://annyasworkshop.blogspot.com/2008/06/mai-from-king-of-fighters.html ).
First I painted metallic white on the shirt to make it look like silk. Then I added black outline of tree branches and after that finished it up with clear red (same red that I used for her bikini) for flowers. Its a very easy design that looks good without being too complicated :D
I hope this helps a little bit more.