When you have lived many years, it may seem like a lot of what you have been through may not be important to tell. Prioritize telling what is important to you and the things that you are most passionate about. Not only will this help you get parts written early that matter to you, it may help you set the tone for organizing your thoughts.
I know last month we talked about outlining everything first, to make sure that nothing is forgotten. However, I think jotting a few memories down as they come to you does not hurt. For one, it makes sure you capture the thoughts at the time, though you may wind up reworking some of them into the narrative of a larger project. It can also help you figure out the tone of a larger memoir document as well. You may discover you write your memories more lighthearted, or perhaps a more serious tone serves best. Writing some initial thoughts down can serve as a helpful playground to build a more structured memoir.