A Classic styled space scene.
Here's what I believe I would do to enhance this image.
First thing I would do is to give the planet's 'Outer Atmosphere' a bit of a glow, but not too much.
Second things would be to replace the shadow on the planet with one that is cast by a sphere, (another planet).
And I would attempt to give the craft some lighting that is more natural with regards to the shadow on the planet.
But if this shadow on the planet is from the craft, then I would choose to do away with the craft's shadow. This would get it closer to what would be considered more realistic in my opinion.
Oh yeah, I would try other starry backgrounds. Some that were a bit more 'in focus'. And maybe selecting parts of the craft to emit light like windows or cargo-bay doors. A sutle glow from the engine exaughsts.
I like that model craft. It has some nice details as I remember.
Keep up the good work. I'd like to see this when your done and it's no longer a WIP.