Really, you have got so much better since I first saw your art! But I wont rant about that, instead I'll try to come up with something helpfull :)
You have a good structure on this, with darker the closer the camera (viewer?) and a nice bloom. But you should probably use a custom brush that's made of a "cluster of pixels", it tends to add "detail" to places were it else is just soft, as the fog and background. Adding a little more dark at the left corners of the picture would also be good, as it would give a better lightning effect, and adding an overlay layer with light blue to the right. Also, you should add shadows on the ground.
Other than that, this is really good :D