The only way I would ever do it is totally anonymously. I would not want anyone knowing it was me, nor would I want any credit for doing so. Hence the anonymity. I would do it solely in the sheer desperation that someone out there may hear my words and at least try to see the sense people apparantly see in what I say.
It would be hypocritical to start one, but it'd be hypocritical not to. I hate people not trying to push change, so it'd be dumb not to try to push change. I don't mind blogs, so long as you're not using them to just speak about what you had for goddamn breakfast. If you use it as a platform to say "Here's what I think about this. Agree or disagree, hope I've given you something to think about.".
Then I just realise that people deserve what they get, and if someone enjoys Gossip Girl and Lil Wayne, simply because it's thrown at them, then they deserve no better.