Ask pg: How do you want us to flag submissions?

The past few weeks, I've found myself flagging front page content more and more frequently. I'm inclined to believe this is mostly due to the site's front page content changing, rather than some change in my own attitude. But I don't want to...dilute the meaning of my flags (and by extension, flags in general, unless you have a way to weight by user the attention flags receive).

So my question is this: what approach to flagging spurious content is most helpful to keeping HN signal:noise high?