Hey, nice work! you obviously have talent and a good handle on shadowing and tone.
Her body and her clothes are near flawless the detail is quite good, it looks quite natural of course it's not perfect but then again nothing is. I don't think you could have done much better. Her posture is very 'geisha'. I suggest you look over the hair, face and hands.
I know hands are very hard to draw so you should practice but never the less it's a good attempt a little more detail would bee good take a look at your own hands, their shape and shading what is the bone structure like. Trust me really giving something a good hard look really helps.
I commend you on using a thick neck, people tend to thin out their necks. I do believe you went a little overboard on the shadow here, she is a geisha long necked and graceful yours does not give his impression.
Her face is to narrow and sharp and lacking detail compared to the rest of your picture. I suggest you take pictures and study them.
Sorry I'm getting a bit lazy....
all i'll say is that it is so pretty!