Capture the spirit of the times. How was your story shaped by the moment in history in which it took place? What wars influenced your politics? What cultural events inspired you? Be sure to include a few important dates so readers can understand the sequencing of the events you are describing. Discussing what happened in the world at large during your lifetime is a good way to make your story more relevant and interesting to those reading it.
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.