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.
You may wonder how to start an autobiography introduction. The answer is simple: the same way you start other essays’ introductions. The main purpose of the introductory paragraph is to grab the reader’s attention and present the idea and theme of your writing. Don’t make the first paragraph too long: between one and three sentences are enough to compose a regular introduction. Try to provide readers with a general portrait of yourself, so they will know more about the main “hero.” Mention your age, significant personal qualities, and principles of worldview. You can also add some details about your appearance in order to make your story more vivid.
Start by writing the story of your life for yourself first. After you edit and polish it, share it with a few trusted people. Then, after you edit and polish it again, share your life story with a wider swath of people. This will help ensure your memoirs are your best possible work, and that your writing is something you’ll be proud of at the end of your life.
Weave in themes. Use the major themes of your life as a way to tie stories together, connecting your past and your present. Aside from the central conflict, what themes have followed you throughout your life? A fondness for certain holidays, your fascination with a certain place that you visited over and over, a certain type of guy you've always fallen for, a rich spiritual life you fall back on again and again. Bring up the themes every so often to help form a cohesive picture of your life.
Incorporate dialogue into your autobiography to make it more personal, recommends history professor Robert Gerlich at Loyola University in New Orleans. Consider including humor when it's appropriate. For example, if you're writing about how you got lost at Disneyland when you were 10 years old and how the experience helped you learn to face obstacles, problem solve and overcome your fears, you might write, "The attendant at Splash Mountain said, 'Are you OK? Did you get separated from your family?' I quickly replied with as much bravado as I could muster, 'Nah, I'm fine. My eyes are just wet from the ride.' I didn't want her to know I was crying."