Recommend content is advisable for E-commerce bloggers. For e.g. Recommended books. A buyer will want to know what more is there in store for him/her.
Newsletter: Newsletter is a great way to keep your audience glued on to all that is happening on your blog. It is best way to know who your loyal audience is.
Grammar - Depending on the language you use, blogging just makes it imperative that you are reasonably good with your grammar skills and proficiency if not a master. Remember your audience is a mix of both; the ones who are experts and the ones who are not.