I feel like blogs are not as important nowadays for personal branding. You are more likely to get people to read your "tweets" on Twitter and build a network and have open streams of communication with people via Twitter. The benefit there is also that you do not need to stick to one topic and can branch out to different topics whenever you feel like it.
But if you do want to start a blog, I'd try to make sure it has a unifying theme of some sort--even if that theme is just being you.
-Jon F
For resume/profile, please visit:
www.TheJonFung.com