Okay, hope you don't mind redlines!!
First off, this is a great base with a great pose, and you've got a great start to an outfit. Short kimono are ADORABLE!
I have complete faith that you'll be able to execute this doll really well.
As for C/C, I think the first thing you should do is look up some references. Short kimono are actually really popular in Japan these days among young women, so you should be able to find good references easily. On the flip side, I know you mentioned looking at costume sites--so if you're going for that cheaper, thinner fabric, let me know, because this will change my C/C!
The second thing you probably need to do is mark in where you're going to put folds. Right now your dress looks really flat and plastic like. Remember how gravity affects the dress--this is what's holding you up on the sleeves. Right now neither sleeve is really affected by gravity or how the body moves. And because of this, you actually have two different sleeve lengths! Kimono silk is pretty thick, so it bunches in big folds, and doesn't have much give to it, so when an arm is outstretched, the fabric really resists. That's kind of what I'm attempting to show with my redline, see? As for the other sleeve, it's going to bunch up around her elbow and wrist, because that's where the body is disrupting gravity's pull on the fabric. The end of the sleeve is going to fall down straight, whereas you have it bending strangely behind her hip.
The obi is also a little odd. Right now it doesn't look like a separate piece of fabric. But obi are thick, heavy, and wrap around your waist like 8 billion times! So it's going to sit around her waist pretty obviously. (Like I said though, if you're not going for an authentic look, and are doing more of an 'inspired by' kimono, let me know! That will definitely change how the obi sits around her waist.)
Her neck line and skirt are also a little odd. Right now, her neck line kind of sits against her shoulders, which is not how kimono are cut: instead, the neck line should WRAP AROUND the neck. This is part of the reason why geisha were considered so sexual: their kimono shows off their neck and part of their trapezius, which was very alluring for men. As for her skirt, right now it looks a bit like she's wearing tulle or something under it! Kimono skirts don't really flare out, so I just changed that a little. However, if you WANT it to flare out, don't mind me-- it could actually be a really cute change.
Regarding her feet, you need to keep in mind how the base's feet are positioned. Right now, they definitely look like she's meant to wear heels. Maybe she should be wearing some cute heels instead of geta; then she can be super fashion forward in her kimono.
Once you've got all the folds in and the fabric falling the way it should, you'll be surprised how obvious the shading will be; just pick a light source and go for it.
I can't really help you more than that until you've got some shading it place. It's much easier to point out how to make something better than how to do something from scratch.
Gah, this ended up being way longer than I meant! Hope it helps, though~!
