Was your aim to succeed as a businessperson? To be the best parent you could be? To amass wealth? To become a musician? To find love or security? Whatever your goal, think of it as the unifying thread that drives your life, shows the failures and complications you overcame, and demonstrates how you ultimately achieved some form of success as the person you are today.
Develop a central theme, main idea or thesis that clearly explains the purpose behind your autobiography. For example, your theme might be about how you overcame obstacles to become a stronger person, or it might explain why a particular passion -- such as mountain climbing or rescuing animals -- is so important to you. Back your theme with details and background information about your life experiences. For example, you might explain that your dad is in the military, so you've had to learn how to adapt quickly to new schools and unfamiliar environments. Or, you might discuss what it was like growing up in a poor, single-parent home, but how your family was always willing to take in injured or stray pets.