A new blog should not add to the existing noise in the blogosphere. Do something outstanding to get noticed.
E-commerce bloggers must carefully write keeping their audience in mind. Everything you post on your blog will speak for your product or service. Your interaction with bloggers in comments and otherwise will give you a direction.
Audience quest: Pay attention to what your audience is asking and give them what they are looking for in your blog. Whether it is content or questions, make it interesting.