Find a list of genealogical questions and answer the questions about yourself. Where and when where you born? What were you parents like? What is your first memory? Filling out a questionnaire is a great way to start thinking about your past.
Talk to relatives and the friends that you have known the longest. Ask them questions about you as well as themselves. Lives are interconnected, and you might learn something from someone else's perspective. For example, ask friends that you went to school with about their experiences at school. Their memories may jog yours, or you could use their experiences as material to help you provide a richer description of your school days.
Read a history book to refresh yourself on the important historical events that occurred during your lifetime. Did any of them particularly impact you? If you have a vivid memory of the event, write about it.
Collect the above information into notes. Add to this any diaries that you have written. Ask family members and friends who kept diaries if they would be willing to share with you some of their pertinent entries that they don't consider too personal. Collect photo albums and videotapes. Visual information can often be more telling than words.
Consider the organization that you desire for you life story. Do you want to tell things chronologically? This often works well for biographies because we perceive time in a linear fashion an you can tell things based on the order that they happened. Another option is a thematic organization where you cluster events and memory on theme rather than when they happened. Consider this approach if you don't like to tell stories in a linear fashion, or if you think that the material would be better understood if organized into categories.
Reorganize your notes an memorabilia into the order that you have selected for your outline: chronological or thematic. Use sticky notes or some type of color-coded tabs to divide the notes into sections.
Transcribe and condense the material from your notes into an outline. The outline should provide an overview and an ordered rendering of events and stories, but it does not need to include complete details. Organize sections from the general to the specific and subdivide sections as they grow more specific into letters and numbers. For example, "I. Childhood, A. Birth, 1. At the hospital, a. Mom's version of events." You should have at least two points for each level so you would follow "a. Mom's version of events" with "b. Dad's version of events." Use your outline to summarize the information in your notes and give you a picture of what the whole project will look like. Refer to your notes when writing the autobiography.
Use the outline as a tool to help you organize and complete your autobiography.