Final answer:
Pre-booking is an effective tool in building a clientele.
Step-by-step explanation:
Making a future appointment with a client while they are still in the salon is an effective tool for building a clientele and is referred to as pre-booking. Pre-booking involves scheduling a follow-up appointment with a client before they leave the salon. This not only ensures the client's return but also builds trust and loyalty. By securing future appointments, salon professionals can maintain a steady flow of clients and a loyal customer base.