Touch up your roots and only your roots. "I've seen so many clients who come in because they touched up their roots but accidentally dyed their ends, too," says Ionato. "The ends of your hair are more porous, so they suck up color very quickly." So quickly, in fact, that the runoff from rinsing out your roots can stain them. To avoid this, apply conditioner to your ends right before you rinse out the color at the top of your head. Or you could try this quick tip: Mix about one teaspoon of cornstarch into the dye to prevent it from dripping down through the rest of your hair.
Add water. Before you rinse out the color, sprinkle a little water on your head and mush your hair around with your hands for a few seconds. "It emulsifies the dye and moves it all around so you don't end up with any lines or streaks," says Ionato. Tweak the results : After your hair is dry, if you're unhappy with the color, you can mute it by applying a deep conditioner to damp hair. Then cover your head with plastic wrap and a hot, damp towel. Leave on for 20 minutes (at ten minutes, blast your head with a blow_dryer), then shampoo and condition your hair. If you're still not happy with your shade, well, it looks like you're heading to the salon.