We highly recommend you do a sensitivity test 48 hours before you begin coloring your hair at home. Wash your hair 24 hours in advance—next-day hair is best for coloring. Right before you start, be sure you have everything you need in front of you. Our checklist: an old towel (in case of spills), hair ties or clips (for sectioning), wide-tooth comb (to pull color through), an old button-down or smock (wear anything you don't mind staining). Check out our handy accessories here.