Remember: Distribute the shampoo evenly, and rinse thoroughly.
Step 1: A Good Soaking
Wet hair completely with warm water (hot water can dry hair). Make sure you lift your hair at the roots, especially in the back, so the water can soak your scalp, where oil and dirt collect.
Step 2: A Handful of Lather
Rub a dime- to quarter-size dab of shampoo in your palms; add a splash of water, and lather it slightly. (Note that, unless you have very thick or long hair, repeating after rinsing is not necessary.)
Step 3: A Proper Application
Apply the shampoo. Starting at the crown of your head, move down to your neck and then along your hairline. Pay attention to the underside of your hair in the back, against your scalp.
Step 4: A Gentle Massage
Scrub your scalp gently in small circles with the pads of your fingers to loosen skin flakes, styling-product residue, and natural oils. Rinse with lukewarm water for at least one minute.
Via Real Simple