Get organized. Some first-time writers begin without doing the proper planning, which results in a haphazard and unreadable autobiography. Break your life up into phases, such as childhood, high school, college, adulthood, and retirement years. When you have all of the categories mapped out, begin adding events that you remember under each heading. The end result is still quite rough, but it is much better to begin with some organization than none at all.
Start writing. Try to stay within one category at a time, preferably chronologically. Doing so increases your recollection and allows you to see connections with later events in your life. Use your project management software to keep yourself organized.
Ask for feedback. This step might be the most difficult of all because your memories are very personal. Nonetheless, the best autobiographies have stern and helpful editors behind their success. One helpful step can be to ask your family and friends if your narrative aligns with their memories. Sometimes we can rewrite the past to our benefit, and having this input will result in a more truthful document. Have courage to listen to criticism; it will only make your book better.
Revise, revise, revise. The best writing is writing that has been worked on again and again. As you read, try to imagine the audience who will read your work. Are there "inside jokes" that you should explain? If you have nicknames for people, you should use their real names at least once.
Publish your autobiography, if desired. Many publishers have shown a renewed interest in the genre, so prepare a query letter and submit it to publishing houses that have published work similar to yours. Keep in mind that you will need to make your book more objective than subjective so that you can reach a wider audience.