This is certainly an eye catching piece that capture's the essence of nature, especially when seen in folklore without resorting to the depressingly popular idea of adding 'glowy fairy magic' to convey a sense of magic that makes the outerglow function in photoshop weep with overuse.
The balance of light in the background and shadow in the foreground does a good job of creating depth, so I must give you points in knowing how to balance colour and light, so even though the patterning of the leaves were the result of leaf-brushes, your skill with them is not that much of a concern. The piece still pops.
I do have some concern of the anatomy of the nymph in question. It really looks like she has two biceps in one arm. Also her right arm arm appears longer than her left when it really shouldn't, especially since her right shoulder is pulling away from what ever she is doing and her right arm isn't outstretched to compensate. Her legs also appear very thin, little to no muscle mass, however if your objective is to make her appear whisper and twig-like (important consider she is a plant) then that it passable and of no concern.
All in all, it is a well balanced piece of art that uses what is thought of to be deceptively simple painting techniques to make an eye-popping and engaging piece of art that from my perspective, reflects the beauty and the quiet chaos of nature better than most. There is room for improvement, but that goes without saying for any piece of art.
Well done. You should feel very chuffed with yourself.
The only really big problem IMHO is the posture of the figure; symmetry of the legs, and that direct angle, doesn't do the figure justice and makes the posture feel artificial. The arms are a little better, but the upper arm symmetry still makes it pretty rigid. Use of a pose reference here would do wonders for it. It's the tiny differences and flow that make all of the difference- like a bit of a twist to the torso, a shift in the shoulders, etc.
There's also a bit of a clash between the style with which the foliage is rendered, which is more abstract, and the figure- though that's a more minor issue. The only way to fix that would be to put a lot more time into the foliage (which might not be worth the effect), or simplify and abstract the figure a bit more (that would be my choice, personally).