Train yourself to use concrete details rather than abstract concepts. Take another leisurely look at what you've written. Highlight abstract phrases such as "I was afraid," or "we had a pleasant time." Replace these abstract words or phrases with something concrete, such as "my hands shook and my mouth felt stuffed with cotton" or "We drank Chardonnay on the Chatterley's sailboat, and as the sun set Rachel and I walked hand in hand along the boardwalk." Was it "a hot day," or was "the asphalt so hot that your flip flops stuck to the tar"? You might go back to the professional autobiographies you're reading and type out a few passages from the books for practice. If you're watching for it, doing so will focus your attention on the concrete. Most ordinary readers won't think about whether or not you've used abstract or concrete terms. They will know whether the writing is boring or interesting. Writing an autobiography with concrete specificity will only improve it.
"Most people don’t think of spiders when they bite into a tomato, but I do. Growing up in southern Ohio, I spent many summer afternoons picking baskets of tomatoes that would be canned or frozen and preserved for cold winter’s dinners. I loved the results of my labors, but I’ll never forget the sight of the enormous, black and white, scary-looking spiders that lived in the plants and created zigzag designs on their webs. In fact, those spiders, with their artistic web creations, inspired my interest in bugs and shaped my career in science."
Create an outline or a graphic organizer of the major topics and ideas you want to cover. For example, you might make a time-order chart -- a chart with event blocks to organize events chronologically. Or, you might draw a cluster web -- a diagram with connected circles -- to divide your autobiography into sections, such as one for relevant background information, one for life-changing events, one for special memories and one for goals and dreams. Focus on reasons why specific events, situations and circumstances were important to you and how they made you feel.