Use Twitter, Facebook and Google+ to Share Your Posts & Find New Connections

Twitter has 271 million active users every month. Facebook has over 1 billion active users. Google+ has over 300 million. LinkedIn is over 300 million. Together, these networks are attracting vast amounts of time and interest from Internet users around the world, and those that participate on these services fit into the "content distributors" description above, meaning they're likely to help spread the word about your blog.
Leveraging these networks to attract traffic requires patience, study, attention to changes by the social sites and consideration in what content to share and how to do it. My advice is to use the following process:

• If you haven't already, register a personal account and a brand account at each of the following - Twitter, Facebook, Google+ and LinkedIn (those links will take you directly to the registration pages for brand pages). For example, my friend Dharmesh has a personal account for Twitter and a brand account for OnStartups (one of his blog projects). He also maintains brand pages on Facebook, LinkedIn and Google+.
• Fill out each of those profiles to the fullest possible extent - use photos, write compelling descriptions and make each one as useful and credible as possible. Research shows that profiles with more information have a significant correlation with more successful accounts (and there's a lot of common sense here, too, given that spammy profiles frequently feature little to no profile work).
• Connect with users on those sites with whom you already share a personal or professional relationships, and start following industry luminaries, influencers and connectors. Services like FollowerWonk and CircleCount can be incredible for this:

• Start sharing content - your own blog posts, those of peers in your industry who've impressed you and anything that you feel has a chance to go "viral" and earn sharing from others.
• Interact with the community - use hash tags, searches and those you follow to find interesting conversations and content and jump in! Social networks are amazing environment for building a brand, familiarizing yourself with a topic and the people around it, and earning the trust of others through high quality, authentic participation and sharing

If you consistently employ a strategy of participation, share great stuff and make a positive, memorable impression on those who see your interactions on these sites, your followers and fans will grow and your ability to drive traffic back to your blog by sharing content will be tremendous. For many bloggers, social media is the single largest source of traffic, particularly in the early months after launch, when SEO is a less consistent driver.