Sue,
I've tried a variety of approaches. Many people say niche blogs work better than blogs that are about everything but the kitchen sink.
Actually, my best response came from a blog in a now-defunct blogging community. It didn't have a niche, but it had lots of exposure because there were a lot of people there and everyone commented on everything. This got a lot of nice comment threads going.
Otherwise, my MySpace blog always gets the most readership simply because MySpace offers much better exposure for unknowns than stand-aline blogs on blogger or WordPress that it's very difficult to attract readers to.
I don't write about current events or fads, so my tags are not likely to be very buzz worthy.
Even niches are hard--e.g., I think you're the only one from Published Authors who's visited and commented on my Writer's Notebook, so readers even with in niche areas are hard to attract.
Malcolm