Looking lovely, hun! i love the colour of her hair, and i like the pose with her moving her hand through it.
Her clothes i see are meant to be see-through- i'd perhaps lighten the colour of the fabric where it is over the skin if that is the case, as it looks very close to the skin colour as it is, but you've done a lovely job with the folds in the fabric.
I think she's looks like an awesome part of this pic, and her nice red hair really draws the eye in.
The mist at the bottom of the water fall looks lovely- perhaps some more emphasis on the running water behind it with different colour tones in the water would be fitting
I do love the creeping vine in the background as well, so more of those would be awesome!
I think the rock could do with a little more texture or differing colours to make it look a little less regular. It might be that green-wet colour around the waterfall as well, since you get that slippery algae and moss when you're so close to water. I know rock is insanely hard to draw and colour- and this is a geologist speaking!
Overall, I think you've done a lovely job, but there are just a few minor things that could be added to it to make it a little more natural.