Identify your audience. To create an effective bio you need to determine who will be reading your bio and what impression you want them to have. The purpose of your bio will help identify the audience. For a job application the audience will be employers, for a speaking engagement the audience will be comprised of people interested in the topic you are speaking on.
Everything happens for a reason. Nothing happens by chance or by means of luck. Illness, injury, love, lost moments of true greatness, and sheer stupidity all occur to test the limits of your soul. Without these small tests, whatever they may be, life would be like a smoothly paved, straight, flat road to nowhere. It would be safe and comfortable, but dull and utterly pointless.
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.
I think the first and best step to getting things out – but not necessarily writing your life story for anyone else to read – is to buy a journal. Start writing about your experiences and painful memories. It will hurt, but the only to get past the pain is to go through it. The more it hurts, the better it will be in the long run to process the experience.
Stick to informal language, unless it’s absolutely necessary to use formal terms. Instead of “utilize” you can just put “use”. Focus on simple language, with one or two syllable words. The only time you should be using higher level language is if you are using scientific terms or describing a technical process. Even then, you should be writing for the average reader.