I would suggest, if you're going to use stylized coloration (the over-bright colors) that you would also do the same to the lady's skin. Perhaps a peachier, slightly more saturated tint of that tone would make her skin look less grey against the brilliant backgrounds in your image.
One other suggestion I have would be to use a blending brush to blend the water left and right to give the illusion of tiny waves and ripples in the water. I realize that that body of water is likely a pond, but water is very, very rarely completely still, so some good ripples and dips and waves would give this image an extra ounce of realism to mix with the stylized colors well.
I'd also suggest avoiding any straight neutral greys, blacks or whites. Instead, use very very subtly colored greys, maybe a little bluish, greenish, yellowish or pinkish depending on the setting, but straight greys look very flat when used in images. Along that same grain, using different values, not simply darker or lighter, in shading and highlighting will aid you as well, to a slightly more realistic lighting. For instance, you can decide that your light source is yellowish, and make your shadows slightly violet using a low opacity brush.
Overall this image is very gorgeous! I love the details on her dress, and the detailing in all of the foliage, particularly the tiny tiny details in the grass Lovely work!
(Also, I remembered seeing this, from another club, or your own submission, so I apologize if I have already commented on or critiqued this!)
I love the colors in this. I think some blurring of the background or some lighting effects may add dimensionality to this piece. I enjoy the details in the background but the details and color make me want to look at that and not the lady which looks like the intended focal point. I think the dress is creative but I don't know how realistic it is to have almost all of the pattern in view on the woman's legs. The anatomy of her legs looks a bit off, it may be the length. Both thighs don't start in the same place so they shouldn't end in the same place. I don't mean to be too critical, I just think there are a few things you could do to really make this a great piece.
Yes, you're right, this need to have more work in it. I said I'll do, but this was more than a year ago and I have do nothing yet. I still want to improve it . I like constructive critiques as yours, thans a lot for your comment