I think more contrast would definitely be helpful, especially on the metal parts. As for ideas for the details, possibly some windows and an decal on the back fin would be pretty good. If you want the ship to be really detailed, you can add large antennae, some holes cut out of the ship (to decrease weight when constructing or maybe battle damage), and maybe a docking bay. If it still looks bland you could always throw on a few ridges and indentations on the edges. The design looks pretty interesting overall. Good luck!