You may not have had the most interesting childhood in the world, but everyone has had a few memorable experiences. Highlight the best parts when you can. If you live in a big city, for instance, you should realize that many people who grew up in the country have never ridden a subway, walked to school, ridden in a taxi, or walked to a store a few blocks away.
What's your central conflict? What's the biggest obstacle life presented that took years to overcome or come to terms with? Maybe it's an illness you were diagnosed with at an early age, a relationship wrought with turmoil, a series of career setbacks, a goal you worked for decades to achieve, or any other number of things. Look to your favorite books and movies for more examples of conflicts.
Organize what you've written according to cause and effect and action and reaction. Ordering events according to cause and effect is a natural process. Your car broke down, so you called a tow truck. That's cause and effect. You received a promotion, so you bought a house. Action/reaction happens paragraph by paragraph. He said "No," so you said "Why?" That's action/reaction. She set a wet glass on the table, so you placed a coaster under it, and remembered how your mother used to crochet pretty little coasters and starch them. That's action/reaction.
These two sets illustrate how you should show the entire action and then show the entire reaction. Don't mix the two together in one paragraph. Write your entire book in this way — action and reaction, one complete set after another. If one part of the set is missing, readers will sense an awkwardness. If you're writing an autobiography, or anything else, action/reaction sequences will make your writing lively and natural. As you expand your ideas, write in action/reaction pairs.