I've been going through the exact same thing.
JesseLovesYou.com » Not Yet a Pro Blogger
You're going to have to find your niche before you start going at this full-bore. If there is enough demand for it, I'll post up my guide on how to find your niche, less gloom and more value-driven content than the "Step 1: How to Find Your Voice" post.
My advice: Is there demand for what you want to write about?