If your offer is useful and genuine you never have to concern yourself with this.
That being said, the answer is knowing why people bounce off pages.
1. Your site misrepresented what they believed they were going to see and was deemed irrelevant.
2. Your customer is comparing your content, products or services with another company.
3. Your customer was impatient because your content was too long, unreadable, or not considered beneficial.
4. Your sites words were too small and didn't adjust to the size of his or her mobile device.
5. Your customer was looking to do research and your site was simultaneously looking to sell.
6. He found your site through misleading advertisements that were not relevant.
Combating these issues can take years and a lot of finese. This is one part technical and one part psychological. If you have the time, pick up a copy of "Thinking: Fast and Slow" - a book that every marketer should have, it details the pre psychology of thinking and how to manipulate thought and lead others to certain conclusions by making them rely on easy thought.
In the coming years "easy thought" will take over the web 3.0 and all sites will cater to emotional facets of interaction. Your ultimate goal is conversion. This will put you a step ahead.