102 Ways to make your blog not suck by Solomon Rothman at Social Media Systems
I don't know if I agree with all of these, but they're good tips. Here are my favorites
10) Use spell check
22) Don’t overload the site with ads
94) Check facts; they’re online and easy to find.
95) Don’t blog pissed off; remember your words are permanent, so least attempt to calm down or be rational
Lastly (though not included on Solomon's list) remember why you're interested in blogging. And don't get too caught up in the advice the pundits throw out.