Barnum was a business man at heart and he wanted to find a way to do exhibitions instead of working in the stagnant position of a grocery store. He was tired of dead end jobs and wanted something more substantial (p. 3). The people in the United States were already used to seeing exhibits and these exhibits were part of pop culture. Barnum just saw an opportunity and he went with it.
Everyone loves a good story and this is one of the reasons why Barnum was so successful. As an example, the Joice Heth exhibit was a very old woman that Barnum built a story around. He gave the public an understanding of this exhibit before he actually showed it and people became so curious about the exhibit that they had to go and see it. He took over the exhibit from some other people who were selling it; Barnum saw this as his opportunity and looked for ways to market her. Capitalizing on the "fact" that she was 161 years old and a slave of George Washington, (p. 6) Barnum was able to create a mystery around her and make people want to see her. Barnum was also smart because he changed Heths story for each of the towns he visited. He elaborated the story where necessary and he seemed to be able to "read" the crowd. This may have meant that he did research ahead of time on the area (maybe through newspapers) and then went into the town and gave the presentation. Although newspapers criticized him, he kept going.
As an example of his genius, when he booked the Heth exhibit, it was at a time when Manhattan, and particularly Broadway was going through a "massive expansion of commercial entertainment" (p. 3). This allowed Barnum to easily fall into American pop culture and find a place that would last him for many years. People were already used to seeing "artful deceptions" and Barnum just created more of them.
Besides his exhibits, Barnum developed a pseudonym to write -- Barnaby Diddleum