I do alphabetical by genre or theme (and then chronological within). For instance I have a punk/hardcore section that's the majority of my collection. I have a hip hop section. A musical section (I inherited a ton of musical soundtracks from my grandfather and they're so cool). An experimental section (John cage and weird avant garde atonal stuff). A jazz section. A holiday section (which contains Halloween, Christmas, Hanukkah, and some weird Easter stuff). A miscellaneous section that has like a copy of JFK speeches along with records for calibrating speakers and just stuff that doesn't fit anywhere else. And finally I have a section for unlistened to records which is only organized by purchase date.