I love this! The way the scene is put out and also the figures. The colours make it look beautiful and the way you put the mist in the back ground gives it more of an effect! This is truly a beautiful picture! The trees are drawn perfect and the leafs on the floor and falling off of the branches make it look more like a forest, the way the figure walks of into the mist is fab! And also how the trees bend and twist make the scene more alive, good work on this piece and keep going
First off, I really adore the color scheme here. You did a good job with the colors. Without the pink flowers/leaves, there would have been too much blue and black. It's nicely balanced here. The way the dog and the cloaked character seem to stand alone between the trees is also a nice touch--it adds a bit of mystery to it, from my perspective.
In the description, you mention wanting this to come across as creepy. I think the reason it didn't come out the way you wished is because of the immense amount of white in the "background." When creating a "creepy" scene, people usually envision dark colors and twisted, almost grotesque shapes. White, unless used with grays or silvers to convey moonlight, usually comes across as the complete opposite of what you were attempting to achieve.
If you wanted to be a little more original with creating a scarier scene, you could try making light sources of different colors coming from, say, the inside of a cave. Doing that gives a sense of impending doom depending on how well it's executed.
Overall, you did a great job with the creation of this piece, and really by itself there isn't much to critique. You just need to practice what colors belong in what moods.