Final answer:
During a shampoo service, cup your hands over the ears, nape, and front hairline to shield them, but you do not need to cover the crown area.
Step-by-step explanation:
When performing a shampoo service, you should cup your hand over various areas of the head to protect them from getting wet or from shampoo getting into sensitive spots. You should normally cup your hand over the ears, the nape of the neck, and the front hairline to prevent water and shampoo from causing discomfort or flowing into the eyes or ears. However, cupping your hand over the crown area is not typically necessary as this area can handle the direct flow of water and shampoo applications without the need for shielding.