In Facebook, engage your fans by posting interactive questions instead of the usual boring statements. E.g. Show 2 colour pictures of the same product, ask your fans which one is nicer.
Having a Facebook page where customers can post reviews, comments and even complaints is essential to building a rapport. Over time, that rapport will turn into brand loyalty. It also inspires word of mouth, as customers/fans encourage their friends to "like" your page, and try your product/service. Try to monitor your company page for a few minutes a day and respond to customer comments within 24 hours or less. You can also sign up to receive an email alert whenever someone posts to your page.