I've run a Shopify store for about 14 months and doing okay sales via organic traffic. As I want to grow the business, I recently started advertising on Facebook. The problem is, it costs me about $12 in advertising to get an $28.50 sale and my profit margin is about $11.50. So each sale has a net loss of $.50 not counting other overhead costs. What are some tips for making paid advertising work for my product?