You're pillow shading, everything is shaded down the middle instead of according to a light source.
Try to be less reliant on outlines too.
I also suggest that if you are working on a ship, you start with a silhouette. Draw an interesting shape, then try to design the large parts. Start with the wings, cockpit and engine. Once that is all done work your way down to armaments, fuel cells, etc. THEN do the little details.