How I usually think realistically when I model. It gives you a good idea of how the ship should look (just don't exaggerate. This is Freelancer after all ^^). Imagine you're inside the ship right now, what would wish or hope to see inside it? Where would the engines be? The windows? Any satelite dish? Any hatches you can open from outside for quick repairs and maintenance? That's how I think when Im detailing and starting with something. I hope this helps, you're the creator of your art, you're the one to decide how it generally should look