Just like in a real life brand/consumer situation, people hate to feel like they're being sold to (badly!), so avoid treating your social feeds as sales-spam territory. Naturally you're going to want to promote sales on a regular basis (unless you're advanced enough to be measuring your effectiveness through less obvious metrics - in which case, good work!) but you need to make sure this sales content is pushed in a respectful and intelligent way. A number of recent studies have pointed to the desire for 'discounts and offers' as one of the key reasons people follow a brand, but overdoing it may stop people from following you, or at the very least stop engaging with you. It might look like a quick win now, but in the long term it will do more damage than it's worth. Get the full story at Econsultancy