First, politeness (not only politeness, but also pay attention to the use of words such as: I think you must know or you must know ~ This kind of words will let customers know your professionalism and will not make customers feel that you look down on him).
The second is to be professional enough (on the one hand, you should understand the company's business itself and the inside story of the industry, on the other hand, you should never belittle your peers, otherwise people will think that you are not stable or arrogant).
Third, the position is to consider customers. No matter what business you do, you are always serving customers. For the sake of customers, on the one hand, it can narrow the distance between the two and reduce customers' resistance, on the other hand, it also makes customers feel that your business is very professional.
Fourth, the tone is neither supercilious nor supercilious, polite and enthusiastic to customers, but neither supercilious nor supercilious. Pay attention to the customer's feelings when you speak, and don't belittle anyone or anything. If there is any unclear explanation, you should truthfully say: I'm sorry, I'm not sure about this. I'll ask it for you later, okay? Remember to reply later.