W. Clement Stone was a Self-made Billionaire in the Insurance business. (Great for people in sales/marketing specifically) In The Success System That Never Fails, Stone shares his story as well as many other success stories in his business and others.
The key to Stone's success actually lies in the title of his book -- The System. By defining a success system, you are creating a recipe for success that can be used by others and doesn't depend on personality.
At age 19, Stone started working with his mother selling accident policies. At age 19, he averaged selling 48 policies per day. Later in his life, he reached a nine-day average of 72 policies per day, and sold 122 policies in one day. He did this using a cold canvas system at office buildings, meaning he had no pre-arranged appointments. Most of us can't conceive of talking to that many people in one day. He might have made some sales of multiple policies for some families, but he must have seen an awful lot of customers in a day to make those sales. I can visualize him running down the halls!
When Stone reached the 72 policy per day level, he started concentrating on building his own sales force. When the Great Depression hit, he devoted more of his attention to creating a sales training program to improve the effectiveness of his sales team, including spending some initial time with new salespersons in the field. He also developed custom insurance policies that would be easy to sell and renew.