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.
E-commerce bloggers can gradually choose to write curated content from other websites/blogs. That always helps because a buyer will generally not spend much time surfing. He/she will appreciate it if you provide most of what they are looking for.
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.