To get myself started, I have received some helpful instruction on how to write decent blog entries and replies; this wisdom was passed to me recently in the form of two other blog entries (what a happy coincidence).
The second discusses how to defend your argument once you have been "attacked" by commentators on your blog. This blog entry borrows from Shakespeare in order to articulate what kinds of defenses one might martial. It was published on my colleague Jean Goodwin's blog "Between Scientists and Citizens" where she discusses how scientists might better communicate with their chosen public. As I do not currently have any commentators on my blog, I will use this advice to (hopefully) develop better arguments in my writing.