Which of the following is an essential pre-service procedure?

The essential pre-service procedure is client consultation. This step is critical as it establishes the foundation for the entire service. During the client consultation, the manicurist gathers important information regarding the client's preferences, nail health, and any potential contraindications. This communication allows for a tailored service that meets the client's needs and expectations effectively.

While sanitizing tools is crucial for maintaining a safe and hygienic work environment, it is considered a routine practice rather than a pre-service procedure. The creation of nail art and applying nail polish are specific tasks performed during the service rather than preparatory steps. Hence, the client consultation stands out as a necessary initial process to ensure optimal service delivery.