Courtesy costs nothing. Be polite when interacting with fellow bloggers and your readers and your courtesy will be visible in your writing.
KISS - Keep it simple stupid. Always keep your blog simple, organizes upto the point. Do not over-flood with unnecessary posts or irrelevant images and keep your content straight-forward.
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.