I agree that Facebook, Twitter, and Linkedin work really well. I also find that companies are jumping onto Instagram and posting images of their business to get themselves out there to interact customers and followers. Instagram is very image heavy with a simple caption much like Facebook used to be, but the way the app is designed allows one to go through an image one at a time, so people are bound to come across the post.
Facebook is good as well, but there's a lot more content on news feeds that posts often get lost. With Instagram one can really show what their company, retail store, and brand are all about. Taking images of the people who work there or even people posing with merchandise tells a story the customer can really understand.
I wrote a blog about using social media for small business retailers at
Hope this helps!