The correct answer is the following.
Listen.
The valet has to listen carefully and pay all the attention to the client. This way the valet pays total attention to the client's indication.
Observe.
The valet has to be aware of the interaction with the client. The valet has to observe all the processes and discover any important issue that could become a problem.
Knowing when to speak and when not to speak.
The valet is there to serve clients. Not to make friends. He has to say what he needs to say and nothing more. Silence is a great asset in his position.
The valet seeks to be a background presence rather than an obvious presence.
This means that the valet has to be very discrete and not be at the forefront of the action. If he is needed he is going to be told.
A valet is not required to supply casual banter, witty remarks.
The valet is not the funny man. He is there to work and fulfill his position. Nothing more nothing less. He has to follow the rules and the protocol.
These important standards serve as the basis of a successful relationship with clients and the correct way to perform the valet's duties.