I would also go for just random structures - "access hatches", random protrusions (see Star Destroyers on any picture search ever for ideas about random boxy structures) and room-looking sections that appear to house people, weapons emplacements (even for fixed, forward-firing weapons, make it look like a bunker or something, low-lying but still obvious), random grills, dips, "shield stuff", "other technical randomness", "wings or assorted stuff absolutely pointless in space", turrets, scanner antennae, radar/radio dishes, docking bays/ports/USD ports/docks-to-temporarily-attach-a-ship-to-the-hull, and anything else you can possibly come up with. Pipes, tubing, and tanks are favorites of the community, and are pulled off in every way from garish and overly bright and cheerful to realistic-looking.
I've even seem gigantic ammo belts for, apparently, MASSIVE C-C weapons ... lol. Those ... they're interesting.
I've seen engine decorations from the absurd to the amazing to the beautiful, but all of them have their own appeals.
Experiment around. Detail can't hurt, but in this game, nice sleek lines usually don't go too well. It's just the blocks, I think, something about it just doesn't fit sleek shapes.
But hey, if you make it work, do it. It's a nice start - better than my correctly named "Mining Monstrosity". Can anybody say "Systems Cube"?