Create sharable content
What content has generally resonated most with your community? For some brands, it may be a sneak peek of a new product, while others may find great traction in a helpful "how to" blog post. Meanwhile, other brands might have a knack for creating viral videos. Focus on the content you want to be shared and make it as simple as possible for people to share it. You can have the best social infrastructure the web has ever seen, but if your community is uninterested in sharing what you have to offer, your efforts will prove futile.
Remove the hassle of sharing
How can you make it as easy as possible to share? One way is to fill in concise, sharable meta-data for sharable content. If a user wants to share something to Facebook and there is no clear description, most people will get confused. And don't make people search around for a share button, either. Place your share buttons in easy-to-find places on your site where people are already active and engaged. When possible, use content that automatically prompts users to share, so that the default option is to spread content around, rather than making it an extra step in the process.
Use social calls to action
Use text, images, or videos to specifically point out the ways in which people can share content to their social networks. For instance, at the end of a video highlighted on your site, place more than just the social network icons. Instead, explicitly tell people to share content out to their friends to make sure they understand what you want them to do. Make it simple and spell it out.