What were the narrator’s desires in the memoir? What was motivating the narrator to share this particular story with the reader? Often, memoirs can be cathartic for the writer. Perhaps the writer was trying to process a year of grieving and loss, as Didion does in The Year of Magical Thinking, or perhaps the writer was trying to describe a childhood in a concentration camp, as Spiegelman does in his memoir Maus. Consider the motivations of the writer for putting down their story and presenting it to readers.

If the project becomes too much for you at any point, remember that writing an autobiography takes time. Take the pressure off. Relax. This is your autobiography. You can make it as brief or as complete as you like, but don't expect to write it quickly. It may take years. If you want to finish fast, you might try the $14.95 Memorygrabber software I mentioned early. The publisher offers numerous free downloadable pages on their website, so you can decide if that approach will be useful or not.
Use chapter divisions to give the book structure. Chapters are useful because they allow you to move on from discussing certain life periods or events. There's a reason we have the expression that we've "closed a chapter" or "opened a new chapter" in life, and it's even more applicable when discussing an autobiography. Chapter breaks allow you to skip forward 10 years, go back in time, or start describing a new theme without jarring the reader too much.
Autobiographies are often confused with memoirs. An autobiography is the inspiring story of a person’s entire life and the societal setting thereof, while memoirs have a narrower focus on the narration of a particular span of time within the subject’s lifetime. It mostly deals with individual’s memories, feelings and emotions. Memoirs are generally much shorter in length because they tend to concentrate on a particular theme rather than the entire life of the person. If you’re interested in writing a memoir, this is a great course to check out.
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.