Hey Nancy, this is a wonderful start
here's some things i see, but just take them as suggestions not a "you have to" kinda thing.
the moon is pretty yellow for a moon, I would of guessed it was the sun if i hadn't read your comment about it being a moon. Also usually when the moon is that close to the horizon, it looks absolutely huge, the light it gives off is more of a white, although on certain moon phases it does give off more of a yellow color.
if you do the moon that close to the horizon, i would think that the shadows off the tree's would be a little bit longer than what they currently are.
You have done a wonderful job on the 2 tree's closest to your fairy. The lighting and texture details on them is awesome. (i know it's not finished, but i'm gonna say it. I hope you put the same detail and feel on the hole in the front of the scene as you did on those tree's)
As for the colors of your fairy, I would give your hole a more of a definite light source, right now it kinda feels really "ambient/flat-ish". My only reason for saying this is to give it a bit more of a dramatic lighting, giving a depth to it. As some say, ...paint with light, but I think the same goes true for shadows...
hmm, as for colors of the clothing, i would go with something complimentary to the blues you are using outside, Which would probably be an orange. Maybe go with some "autum colors" unless you want to give it a "spring" type feel, then go with some greens. Also if you want to experiment, play with a deep red outfit as well. I'm assuming you are using photoshop for this image, if you are just put these all on separate layers so you can swap them out quickly and easily.
and as a last suggestion, I would maybe try matching the color of her eyes with the same purple used in the wings, it could really make things pop!
This is a great start, and i can't wait to see it finished
...best of luck!
-agentxi-