Hot water opens the hair cuticle, allowing pigment to seep out. To clean hair between washes, spritz dry shampoo on your roots.
Look for a mask with moisturizing and repairing ingredients (like shea butter, glycerin, and keratin), and use it from midlength to ends once a week.
Avoid heat styling.
If you must use a blow-dryer, flatiron, or curling iron, first spray on a heat protector from roots to ends. It helps seal the cuticle, preventing color from getting dull, says Daniel Villano, a stylist at the Frédéric Fekkai Fifth Avenue Salon (and Michelle Obama's colorist).
Buy yourself two more weeks between dye jobs.
When your roots start showing, dust Color Wow Root Cover Up ($35) on the regrowth. The long-lasting formula comes in four shades (blonde; light, medium, and dark brown) that perfectly blend with your haircolor, and stays put until your next shampoo.
Tips for Coloring Your Relaxed Hair
Always see a professional.
Relaxed hair has been weakened by chemicals, so the strong ingredients in permanent dye can be especially damaging. An experienced colorist will likely cover your roots and darken your shade with a gloss or a semipermanent dye containing a low concentration of peroxide.
Avoid going lighter.
Because relaxed hair is very porous, it quickly absorbs bleach (the chemical used to lighten). The combination of bleach and acids in a relaxer has the potential to literally disintegrate your hair.
More on Color-Treated Hair