Debbie Weil knows her stuff when it comes to Marcom. Her blog, BlogWrite For CEOs , is a great resource.
A recent posting, titled, Good blogging is good writing... with a twist lists a Top 7 list of blogging tips she gleaned while at BBS2005. The points were originally presented by Halley Suitt.
Combine these points with the 4Ps of Blogging and you've got a great background to get started blogging.