In what manner should I speak with the customer?

With a good tone of voice - A clear, friendly voice suggests much better customer service than an indifferent or inconvenienced one. Greet callers in a polite and professional manner. Use the caller's name during the conversation to build rapport by asking for it.

By being consistent- It is important to bring the same energy and the same tone of voice to every call.

Be personal, not transactional - Although most people use a transactional approach when dealing with customers, having a personal approach can work better when booking a hotel. This means that you get to build better rapport with the customer, they easily let you know all the information you need to know in finding the best hotel that would fit their needs and you avoid dead air by having a natural conversation with them.