Which of these practices is essential before serving clients in a salon?

Washing hands with soap and water is critical before serving clients in a salon because it is a primary practice in maintaining hygiene and preventing the spread of infections. Proper handwashing removes dirt, bacteria, and viruses that can be transferred to clients during procedures. This practice is essential in the esthetics field, as it helps protect both the client and the practitioner from potential health risks.

While wearing gloves is important in many situations, it is not a substitute for handwashing. Brushing hair, although a necessary skill in many beauty services, doesn't directly contribute to hygiene practices before starting any treatment. Changing clothes may be relevant for maintaining a professional appearance, but it does not directly address sanitation and health standards. Therefore, handwashing stands out as the foundational practice that is crucial for client safety and cleanliness before any salon service commences.