I arrange my CDs (and used to arrange my LPs, before they got moved around so often that they have no particular order) in this way:
Of course, these are RULES, so it's never that simple.
Bruce Springsteen won a Grammy for contemporary folk. Am I to put that album in one category and, say, "Born in the U.S.A." in another?
A more striking example is k.d. lang, who started off as a country artist and became a chanteuse. It's much easier just to look under "L".
Besides, an alphabetical list generates a more interesting shelf read: Bill Miller (Native American/popular), Glenn Miller (big band), Roger Miller (country), Steve Miller (rock). "Shelf read": a librarian must have written that.
In the pop compilation category, I violate my own rules (but they're MY rules, so I can do that), in the placement of tribute albums, mostly because I'm having an increasingly difficult time REMEMBERING what they're called. So I've moved:
You may think this is anal. *I* think this may be anal. But I can FIND items in my collection, which is all a librarian can really want.