Customer acquisition is the only pillar of social media that cannot stand alone. Brands can attract tens of thousands of fans and followers without ever acquiring a new customer or making a single sale attributable to the channel. Ouch! That's scary to think about. Imagine all of the resources that have been invested in social marketing over the last five years that haven't generated one iota of return.
Companies that offer deep discounts (like Woot!) draw new customers with incredible offers. Others like Apple have passionate fans that drive social activity with minimal company involvement. Everyone else has to rely on their customers to attract prospects that can be converted. Communities must have a solid customer base foundation to succeed.
Early corporate adopters of the social channel were often disappointed in the results and stopped participating. Their frustration is easy to understand because they expected their activity to attract customers. When it didn't, they were told that they weren't remarkable enough and shown success stories from Apple and Zappos! No one bothered to explain that the companies used for examples were exceptions. They had an established fan base before entering the social arena.
Building a solid community from your loyal customer base is the best way to attract quality prospects that can be converted. The people who use your products and services are the ones who are most likely to have friends and family that would like your company too. You have already established a trusted relationship, so you don't have to do the "like me because I have great content dog and pony show." You have great content because you are communicating with your customers.
Use every opportunity to encourage your customers to participate in your social communities. Tacking a link at the bottom of an email or webpage is availability, not encouragement. Sending an email with the sole purpose of increasing your customer activity on your pages is encouragement. Adding an added value like a discount is motivation. People will participate if the reasons are compelling enough. Finding the things that motivate your customers to join your communities is a top priority in a successful social strategy.
After you've established your core base, encourage them to invite their friends. The best way to do this varies by company, but finding what works with your customers is worth the effort. They become your best sales team. This is almost perpetual motion marketing. You treat your customers right and encourage them to share with their friends. They share their experiences and attract new customers. You treat the new customers right and encourage them to share with their friends. They share...well, you get the idea.
There are two things that make social media work as a prospecting channel: Treating customers right and encouraging them to share with their friends. Expecting anyone to introduce new people to your business because you have great content and are likeable is an exercise in futility.