First of all, it is worthy of recognition to be considerate of customers. I also hope you can stick to it, because although sales depend on performance, there are still many problems that cannot be ignored.
Sales Skills I suggest you read more books on marketing, which contain many cases to help you analyze your learning skills. Then combined with your actual situation, you should be able to get started soon. (such as accurate positioning of customers and price negotiation skills. )
About the boldness you said, I will understand it as the ability to control for the time being. A good salesperson actually has a good psychological analysis ability. What the customer thinks and what he says represents what kind of goods and services he wants. What is his psychological price and so on. It is necessary for salespeople to control from the first scene. So I suggest you read some books on sales psychology.
Finally, it is not enough just to master sales skills and psychology. We still need to work hard to improve our cultural literacy. Externally, including dressing. Internally, such as talking, treating people and so on. This is very difficult, and it is difficult to do it without hard work.
I hope it helps you. I wish you success in your work and better self-expression in the workplace.