I made this tower in Google Sketchup so I decided to throw it into terragen and light it up!
Your image does have potential Xenonnoble28 :)
I would get rid of one of the moons and-or make the little ones a little more smaller.
The tower is not in the foreground enough . The image looks a little like bad cropped.
You can bring it more in the foreground-middle or change the POV a little.
It is your image of course ;)
It looks nice , keep it up !
Keep the large moon on the horizon. The other two can be smaller. I would also see if the foreground can be illuminated better; not too much. Just enough to see the trees lit from the large moon.