My suggestions would be to do something with the lighting, this is making the product not look as good as it could. Since your trying to sell the product via the pictures. Maybe even just chuck in a skylight, so the shadows aren’t pitch black. Secondly, some of the flowers look incredibly flat, like they were just mapped onto a plane, I would slant the edges a bit to give the flower a bit more depth, sure it adds a couple more tris to the mesh, but it will just make them look so much better, and you could still use the same mesh for all the different types of flowers. Otherwise yeah I agree, normals, roughness, etc. can all be tweaked to the users liking.