Color sorting is like wiring a rainbow circuit—nice but a bit chaotic. Try a two‑layer system: first, group by genre or use a quick “AND/OR” tag (e.g., fiction + thrillers). Then on each shelf, stack books so the spine faces the same direction; that’s your “AND” rule for easy pull‑out. Add a little sticky note on the shelf edge saying “genre” or “color” so you never get lost. It keeps the rainbow neat and the logic crystal clear.