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.
Tutorials: For Business Blogs, have tutorials that teach your customers how to use the product/service, what are the features of the product/service and keep your customer views open for them to read.
Spare time to read - Blogging is not just about writing but also about research and reading. Read as much as you can to learn new things and ideas that you can experiment with on your own blog.