Your pack looks nice. If you can publish a WebGL demo on your publisher website, prospective customers can see how it feels in Unity. Make sure to use good post processing such as Unity’s new Post Process Stack to show it off to best advantage.
Fantasy and apocalyptic environment/prop packs are always popular categories, with sci-fi coming in a close third place. Choose one category and make a lot of packs in it. Developers often look for packs in the same style that they can use to fill out their whole game world, so you’re more likely to get multiple sales.
Thanks for the advise we’ll certainly look into doing a web demo and what you said about those categories is interesting we’ve actually started on a Sci-fi pack so I do hope your right!