:sl:
The proportion of the moon is too big in comparison to its surrounding elements (the lighthouse or the boat).
Try adding different kinds of shading to the water, to give it that 3D effect and make it appear more vivid.
I was going to mention something about perspective drawing,but I don't know if its too much info fo what you're looking for...:)
(if you're interested, here's a link:
http://www.olejarz.com/arted/perspective/intro2.html)
Anyway, lastly, I'd suggest adding a few more elements to the right side of the drawing, since the drawing appears to be concentrated in one area, then rather empty in another (compare the right side to the left side...)...adding elements or even different drawing techniques(such as shading,like you did), can make the image appear more balanced.:)
Nice drawing all in all!
:w: