Deductions for side businesses done on eBay, Poshmark, and Facebook

Hello, I started a side business of reselling good over Ebay, Poshmark and Facebook. Each one I have over $600 in sales so I know I will get a 1099-K.  I am wondering what can I deduct to offset the sales in addition to the cost of goods sold? For example, can I deduct the part of the house we use to store inventory, take pictures and prepare products for shipping? Can I deduct the miles/gas that it takes me to go to the post office and UPS to mail packages?  Thank you!