Identify the main characters. Every good story has interesting characters, friends and foes who help move the plot along. Who are the characters in your life? It's a given that your parents will play a role, along with your spouse and other close family members. Think beyond your immediate family to others who have affected your life and should play a role in your autobiography.
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.