How to become a better salesman?

I am often asked: “What should I read to become better at sales?”
I answer: “Your phone book.”
Dial the first phone number, try to sell something. You will be rejected. You analyze the reasons why you were rejected, change your script, and dial the next phone number. You will be rejected again, so you analyze again, improve the script, and dial the new number.
By the end of your phone book, you will become a master of sales.