Yeah - place blocks in shapes until something looks right.
Honestly, just step back from it, figuratively and literally in-game. Slide your view back, and look at the whole hull. Find a shape, a design, an artistic flair, some little piece, anything you like, and then compliment it. Build off of what's good about it. Find a general shape for the whole thing in your head if you can, or if you can't, find a reference point. Something that worked. Build off it - add shapes that fit with it, expanding your hull or contracting it to end. Add onto that with similar or even wildly different but complimentary shapes and devices.
If you can get one thing you like, if you just build off of it, it will work.
And once you've built a part of it, if you can't find the next flash of inspiration for a shape, do what I do: find the logical and necessary next step. I was building a ship, and I had the side down, but I couldn't figure out a good look for the central hull or the bottom ... so I said, what must I build next? And I found it. The result isn't art, I'll not build such amazing artworks as you can find in Comm. Content at least for a long time, but it looks good. It works as a unit. So it's complete. It's finished, it's done, and I don't have to fiddle with it to be perfect.
Now that it's done ... if I ever want to, I can go back.
TL;DR the rambling: Slide back from what you have, and find a point you like. Add complimenting things on there - add to what you like, or make something contrasting to draw the eye. Find spots you can build in - find locations for devices and shapes, shapes that hint at purposes beyond just "blocks" or "wedges" but to grills, vents, weapons, access hatches, battle scars, machinery ... and when all's said and done, you'll find that you've either built a ship you like, or pieces you like. But make certain you don't sacrifice aesthetics to functionality. We can all build Borg cubes - we want to see masterpieces. If you can't build a masterpiece, build something you can be proud to fly around in. It may not be the prettiest box for the biggest gun, but it's got the gun and it's not ugly.
If all else fails, make a reproduction, or several, of ships you like. Get some ideas. Use them or adapt them or find a better one. It just requires work and a bit of vision, or inspiration.
TL;DR too bad. I'm not making that point any shorter, lol.
FIRST!
Good luck. Post some images, maybe those of us who like to pretend we know what's going on can give you some ideas. We're a helpful bunch.
(Yes, we are! -Oh, really?- YES! -Are you so sure?- OF COURSE I'M SURE!)