About Sales

need to do LOW poly? I have done my models in vain! ??)

i believe your work worth much more than 3$, even customers become suspicious when your models have such low price, be reasonable

You need more different models. And if you say LOW poly then you need to show wireframe without smooth mods.
Try to spend some time pretending customer and look at other people products: you will see what they have, what you like to know about product, what information must be added, what kind of model views they have etc.

Thank you jonjensen

Well, my sales dosen't either, so I may not be the correct person to give you advise. However. You have allot of similar models with different texture. When you get more different things in your shop, sales could get better. But don't invest more time on furniture, that category is already way too overcrowded. The chances for making money there is small.
Another thing. You could put up the prizes a bit easily. This one fx is worth more than 3$ :https://www.cgtrader.com/3d-models/exterior/house/stylized-medieval-house-5dae710d-89f9-4d73-aefa-7b824224083c