I think if you want to sell your models you have to have a blinkered view on it and that you need to specialise in one or two areas of expertise. Just like marketing anything else you need to find out your target audience and play to them. I focus on medieval models and the games industry and I do quite well (although not this month for some reason, it appears people prefer Christmas to work!). I not only focus on medieval, but I also focus on a style of model. My Twitter account is pretty much followed only by game developers and I share my work there as upload here and elsewhere. Facebook, a blog, linkedin, Discord, Pinterest are also places that you should be posting on each time you upload a new model. If you can, give your model a back story and a good description and supply as much information as you possible. Good luck in your future sales and happy winter solstice!