When you write your memoir you can do it by memory and then piece the short pieces together adding transitions between the pieces or chapters. An important thing to remember is that each piece must start with a compelling sentence that leads the reader into the action right away. It’s like a scene in a movie. If you can see it, you are showing us and not telling us. Save the telling for connections between scenes. So, start with action, connect with a bit of narrative, more action (scene) and when ready end with a question, a mystery, a conclusion left partly unknown or sometimes with a conclusion. Remember life is really not neat. Life is quite messy. Write so the reader is reminded of this and your memories will ring true. Sometimes to conclude with what you started writing about is satisfying but don’t do it all the time. A lot of the conclusion came in time, another time. The readers want to be with you in the unknowing parts of your life too.
The advantage of writing this way is that it can be done a chapter (memory) at a time. When you have the time, you can write about how two of you hitchhiked to Florida and ended up in a trailer camp with your own trailer for the summer, free of charge. Was it the summer you learned how to deep sea fish really well and fell in love for the first time? Then the next time you have a block of time to write, you can go back to your senior year in high school and show yourself talking to a teacher about philosophy. Would it be interesting enough to you and help you find a job you want or will psychology replace philosophy? Maybe a scary event at first college tour you went on helped you make up your mind of what to study. The story may be of how answers come to you when you’re least expecting them.
The disadvantage of this collage technique is that without a clear theme and outline you will find that you overwrote and some chapters are not necessary. Often then is a dip of interest in the middle of this technique, a dip that is less interesting. Sometimes the theme doesn’t show up clearly enough. However, some writers don’t care. They want enough of it down to rewrite and hone it down.
If it feels natural and you’re okay about rewriting, go for it. It’s easier to cut back than to add more information. What counts is not the first draft but the finished draft and you have “miles to go before you sleep” and it can be fun and exciting all the way! Write and enjoy the process.