When it comes to social media, the thrust of any strategy is aligning your core message with your audience's needs. But there is a reason it's called "social" media. How does what people you know and "like" affect how a message influences you?
A key strategy for success in using Facebook and another social media sites for brands is to make use of the influence of "friends" and expand on an individual's social networks to enter their sphere of consideration. If your friend (or colleague) recommends something, "likes" it or "shares" it with you, you're more likely to pay attention than if the message comes from a random unknown brand.
So how does the psychology of influence work? This infographic from Pardot does a good job of summarizing it.