Before using the Crazy Colour Ruby Rouge hair dye, it's always a good idea to do a strand and sensitivity test. First, shampoo your hair with a pH neutral shampoo and don't use conditioner. Then towel - dry your hair. While your hair is still damp, put on gloves and apply the dye evenly. Leave it on for 15 to 30 minutes, then rinse thoroughly until the water runs clear. To keep your color looking great, avoid dandruff or harsh shampoos as they can strip the color quickly. Use a sulfate - free or color - friendly shampoo and wash your hair as little as possible. After shampooing, rinse with cold water to seal in the color. Also, stay away from too much direct sunlight and swimming, as they can fade the color. And always do a patch test before using the product regularly. If you feel any redness or itching, stop using it.