Like growing any social following, you need to interact with others on the platform. Start sharing their stuff, commenting on their posts, building relationships. Make friends.
Every one says, content, content, content. While that is part of it, that is only one part of it. Content alone probably won't blow up your following number. Least for most people.
I've also found that blog commenting, and building relationships with other bloggers can have the positive side affect of growing your social following as well.