Once you have chosen your preferred outlets (see Social Media: Rising Above the Clutter Part 1, published yesterday), be sure to not just post, but engage with your community. This means replying to comments, commenting on others' content, and engaging with the community in the same way you want them to engage with you.
This two-way communication is key to building brand loyalty with real relationships. Also, by spreading yourself onto others pages, you are exposing their followers to your brand.
But there are other ways besides commenting and sharing to reach out to your communities. If you find a blogger who posts on topics that are relevant to your business, you could send them product samples or give them a product pitch. If someone else is writing about your product, readers may be more likely to believe their claims. Incentivizing a few bloggers to post about your company will have greater returns than a company's single blog post.
You can also engage your social media communities by starting a social media contest or giving out discounts to your followers. People will engage you're your brand because they are excited by the reward your brand offers; so don't limit the rewards to just newcomers. You also need to occasionally offer benefits only to people who are already in your network to encourage people to stay engaged and reward loyalty.
The purpose of social media is to connect people to people; not people to businesses. As with most things, there are exceptions, like LinkedIn, but to be a successful social media site, you must respect the purpose behind the outlets. The key is to invest in customer relationships without being invasive. The real way to win in the social media game is to be balanced. You need your customers to know you are there but not become overwhelmed by your messages. You also need your regulars to know you are listening to them and appreciate their active participation.
In summary, the best way to rise above the clutter is to not become a part of it.