For the face, it'd be great if you could show a front / three quarter / side close up, like this (without the hair, ideally)
Use Asoro heads as a reference, i can already see that the distance between eyebrow, nose and chin are not "equal" distance. Take my stuff with a grain of salt, cause i am by no means a character artist. Look at Andrew Loomis sketches and asoro heads to figure out where your face planes are and work them out firstly in a very rough pass in Zbrush or blender. Afterwards, if you need more dense mesh, you could subdivide it to get more density to work with. Your sculpt also have some bumpiness around chin area and head because of this . keep going!
heyfor the folds, did you already try the cloth simulation options you have in zbrush? might be a good try to get more realistic looking folds
Try this thing
Here's a little drawover I did for mainly the cloth. I think you can keep it simple, and try to focus on the big shapes of the wrinkles and folds. If you think about gravity, the wrinkles will probably come down from the shoulders, as thats where the cloth is resting when it is on your body. The best way though would be to look at reference, and study what is happening. Other minor changes I made on the drawover was the breasts; I felt like they could look more natural if they "sagged" more, and I tweaked the middle part of the corset to look more comfortable.For the face, it will definitely be tough doing it for the first time. I did a stylized character too fairly recently, and the problem I faced was getting a good balance of realism and following anatomy, but also pushing the stylization that I wanted. I think many of the points that were made already by the others are very good, and the only thing I would add is don't be too timid with the details. For example the eyes are very big, which is fine, but the eyelids are very thin in comparison, and the planes of the face surrounding the eyes are also kinda too smooth and not giving a good volumetric feel to the face.Hope that helps
Need more reference on the folding and creases of the clothes. Maybe take those on yourself. wear baggy pants, tape around your knees and take pictures, see how the folds fall.