3 of 6
3. A cold-water rinse makes your hair shinier.
Hairstylists love to spread this gospel. Their rationale: The icy water will make the cuticle of your hair close so it's flat (and light-reflective), not ruffled (and dull-looking). Your hair, however, contains no living cells—it doesn't react to cold (or hot) water, says chemist Mort Westman. Use conditioners and styling products that contain silicones and oils to smooth the cuticle. And limit damage to your hair from straightening treatments, hot tools, and frequent dyeing.