Although a new hair color can transform your entire look, if you dye your hair a darker color and don't darken your roots between colorings, your hair won't be as attractive as it could be. Learn to dye your own roots, since going back to the salon each time you need to touch up your roots would be cumbersome and expensive, and roots usually need to be darkened every three to four weeks. Whether you have dyed all of your hair or just have highlights, you can darken your roots at home.

Obtain the appropriate shade of hair dye. The "Cosmopolitan" website recommends that you purchase a dye one shade lighter than your hair's current color, since commercial dyes often run dark. If your first dye job was done in a salon, ask your hairdresser if he has a touch-up solution you can use between visits. Many stylists will give you such a solution because they know dyeing all your hair each time your roots start to show damages your hair.

Mix the dye in a plastic or ceramic bowl. A metal bowl can change the dye's shade. Follow the mixing directions on the box of dye; don't mistake the fact you're only coloring a small portion of your hair as a license to improvise.

Paint the dye onto your roots. Stand at a mirror in a room with bright light, and use a paint brush or hair color brush that has a width of at least 1 1/2 to 2 inches. Leave the solution on your roots for the length of time recommended on the box.

Do a strand test to see how fast your hair absorbs color if your dye came in a box that doesn't recommend a dyeing time. Apply a small amount of solution to a few roots, let it sit for 10 to 15 minutes and comb it out. If the color has been absorbed adequately, dye the rest of your roots for the same length of time. If the color is too weak, do another strand test and let the dye set for slightly longer. Fine hair tends to absorb dye quickly and coarse hair absorbs dye slowly. Do not leave hair dye on for more than 20 minutes.

Pull the dye through to the ends of the hair using a comb. This evens the color and distributes the dye so it does not appear sticky or clumpy. Do not wash your hair for a day after coloring. Use color-safe shampoo and the conditioner in the color kit when washing your hair once you've dyed it. Avoid direct sunlight or wear a hat or bandanna. Follow the directions on the box if it recommends other types of aftercare.