Use simple words and phrases: Think from reader’s point of view. Do not imagine that everybody will know what you know. Readers will be fed up if the story narration demands scrambling for a dictionary each time they come across a big word or surfing the net for new topics that you haven’t described at least in brief. Use only simple words and phrases that everyone can understand, and when introducing a new concept or subject, explain it so they know what you’re talking about.
After considering these factors, the next step is writing a draft. Start by looking through the best autobiography openings you can find and figure out which you can use as a model. Make sure that you write in the first person since that’s what autobiographies are all about. Never switch back to second-person or third-person and be consistent in using the first person point of view throughout the entire content.
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."