Well there are advantages and disadvantages to planning, as sometimes what might seem like a good idea might not look so great in execution, while simple overlooked ideas can often be best. Screenshots from other games can offer inspiration and information on just how to execute the theme, but the set will probably just look very similar to those screenshots.

I am personally not interested in making a shipboard tileset. The idea of making something detailed and complex sounds great and I'd love to take the challenge, but only if we are intent on making something original, that looks amazing, and very imaginative. In other words, all the people have to be as motivated as I am to make this work, and that means making something that might seem like a stupid idea at first but in actuality is a work of genius.