1. You must be very knowledgeable about the product you are selling.
2. You must have unlimited enthusiasm about the product.
3. You must know what problem(s) the product can solve.
4. You must have empathy.
5. You must be resilient and persistent.
6. You must be willing to promote your product/service.
7. You must be willing and able to sell.
8. You must be sharp and quick witted.
9. You must be friendly and easy to deal with.
10. You must be trustworthy.
There are many more traits you should have if you want to become a great salesman/woman but the above 10 are about all I can immediately recall now.