Rojero, same here. I have
zero artistic ability, but I still want a shipset of my own. I've started, then aborted one, I may revisit it soon.
Some more suggestions ...
Select an intermediate hull size, for example, light cruiser or battle cruiser, and decide how it should look.
Have smaller ships be the same basic size, but smaller, and simpler. Have larger ships not only be larger, but have more "things" on them.
Look to any sci fi tv show or movie to see what "dodads" your ships should have. I saw once how the nacelles on a shuttlecraft for ST:Next Gen were actually painted disposable razor handles -- so inspiration can really come from anywhere.
I really liked the missile picture from the terran shipset and wanted to slightly modify it. I tried to do this a pixel at a time.

I've abandoned that plan (try not to be too shocked guys). I'll go with the symetrical sphere so many shipsets seem to use. The point here is don't be afraid to abandon something that turns out to be too difficult and approach the problem a different way.
Not every shipset has to have every image in it be a work of art.
