The most important part of upselling is understanding what the customer needs and wants. This can be done through active listening and reading the customer's body language. Once you understand what the customer is looking for, you can then offer them products or services that will meet their needs. Upselling is not about selling the most expensive product, it's about finding the right product for the customer. It's important to ensure that the customer feels like they are purchasing the right product mix and getting value for their money.