Let's say first up that you are not likely to get a lot of direct purchases from Facebook but substantial benefits can still be gained. Facebook is a great (free) way of communicating with your customers on a digital level but to get results you need to avoid the hard sell and introduce the human factor.
Last Saturday I posted on my business Facebook page about a popular product in my range. I very carefully prepared a concise description of the products benefits, added a clever (in my view) photograph, and a competitive price. I received a rather disappointing 3 "likes". The week before I had posted a photo and story about my Grandaughter's first day working at our stall and received 9 "likes". Both posts presented my business to my customers but the social interest story obviously won out. That doesn't mean I will stop posting about products. My customers expect to be kept up to date particularly about new product arrivals. But I need to include social interest stuff as well.
Facebook is described as being a bit like doing business in a pub. You wouldn't expect your bank manager to come in and give a hard sell on interest rates but meeting and socialising with him might make you more likely to give him your business. It is all about establishing a connection with your customers.