Select the Community – What community actually suits your business. You may do a research about your business. Whether your company is mentioned in tweets? You found a video uploaded in you tube about your company or Do your corporate blog have a like in facebook etc.
What social network works best for you?
Before you choose the social network, you have to analyze the nature of business or nature of the product or services you offer. If your business have a great portfolio to share with, facebook and pinterest would be a great option. If your product needs instant support, Twitter would be the best option for you as your tweets would reach even the mobile handsets. If you are looking for b2b customers, Then linked would do good.
What a blog would do?
If you are provide a service or you are a professional. You would provide lot of free quality content to people in the social web. A blog would do the job. It should be well connected with social websites by providing share buttons, like buttons and tweet button. There would be a fair interconnection between your social networks and blogs.