How to sell a product

I haven't sold a single model, can anyone please guide how can I increase my sell.

You are more or less selling stuff that is everyday items, which is good, as most people hunt for boring, not highly specific bits and bobs for the background of their projects. But they are a bit pricey. For 15 bucks people expect a collection of such things nowadays, not a single light bulb, and a single spray can, and whatever.

Products with bags and creasing packing materials should crease in more spectacular ways to get the attention of anyone who is out for bags of food products.

That biscuit item is textured lazily on the sides and does not feature displacement in the middle. Also pricey on its own, should feature at least a companion model with one broken in half or something. All of your items could be beefed up with details like that.

Water droplets on the soda can, ice cream cup half way torn open with actual ice cream inside, grass and dirt marks on the footballs, whatever.

Add sexy details, merge separate things into collections, consider lowering prices on things that are a ten minute job for an experienced modeler.