1. Most hair dye kits come with a tube of deep conditioner. Use this right after you rinse out the dye, then do a deep-conditioning treatment at least once a week after that. It will help preserve colour and shine. 2. If you wish to preview your desired colour before applying it completely to your hair, do a hair-strand test first. Cut a small piece of your hair, apply the hair colour mixture to it, rinse the strand and dry it before assessing the colour.