My theory on labeling my blogposts is that labels should be broad rather than specific. This is partially for the benefit of my readers (hi honey!), so they don't have to negotiate an endless list of labels, and partially for my own benefit so I don't have to compose and keep track of such a list. Thus, I have labels for Religion and Science (but not for the Anthropic Principle or Big Bang Cosmology) and for Philosophy (but not for Epistemology or Philosophy of Mind). Occasionally I've found it necessary to be more specific. So from Culture and Ethics I made labels that dealt specifically with Homosexuality and Abortion; from Books I made a label for Quotes; etc. But I was having a difficult time with labels for particular people. I write enough about C. S. Lewis that I knew I should have a label for him from day one, but over time, I've realized that there are other people who I mention frequently enough that they warrant their own label as well.
Recently I experimented with splitting the labels listed on the sidebar into subject labels and people labels. Then I started going through my posts looking at the people (philosophers, mostly) who I've mentioned more than once. You can probably guess how that ended up. Just going over my posts for the last several months I had more people labels than subject labels, because people labels are inherently specific, and most of them only had one reference. So I scrapped the whole thing, just went back to "Labels", and included two new subjects: Philosophers and Theologians. In the future, if I focus on a particular thinker several times, I'll try to give them their own label.