Oh, nice pic, before you Pen it I'd edit a few things.
![Image](http://img85.imageshack.us/img85/4928/editeddo5.png)
The Green parts are where to add more land and stuff, it sorta disappears or is wonky/unblending.
Blue parts are where to add a shadow
Orange parts are where to get rid of the shadow (the Tree's shadow is more bunched together branches doesn't really look like a shadow of a tree)
Purple parts are rounding off parts, the clouds look very jagged like drapes of cloth flowing in the sky make them more cloudy? (lol)
Pink parts are where to add an effect, like a glow around the moon to show it's the moon and that it's night time.
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Nice pic though, just improve it before penning?
Overall: 7/10
PS: maybe add more detail to the Dragon?