I had the same problem because I also am doing a sci-fi comic and had to draw spaceships and had never drawn them before. I looked at what other ships looked like and made them a bit similar. I also took into account actual ocean ships since the basic parts are a bit similar and the parts are named the same and I wanted to make sure I was using mostly proper terminology.
I did a few sketches in my notebooks to get what I wanted, but I think I should have done more. I recommend looking at a LOT of different references and doing a good amount of sketches, trying to improve on the other. Make notes about small details you think might be easy to miss when drawing, what parts should be toned or colored a different way, if any, etc.
When you get to the actual page, then is the real challenge because now you have to make sure everything is in perspective correctly. Perspective to me always looks different than how I see it in my head. I've slowly gotten better at it. Make sure you do dramatic angles and have good shading. Use tools to help with the curved parts. Take into account if there are glass/windows and you can see inside.