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.
Avoid using SMS abbreviations in blog post and at least run the post through a spell-check in MS-Word before publishing. If the bloggers cannot take the time out to write proper English, why would the readers bother reading through that cryptic puzzle?
Share your personal experiences on your blog occasionally. It makes your posts more real and helps your readers connect with you.