Most of us write the first draft of our memoir chronologically, setting down what happened in order, or thematically, thinking of what happened and expanding from that time, place, or feeling. Both are terrific ways to generate a first draft.
But memoir is a rare country. Making the map of personal experience, writing the guide that says, This was five stars and everyone should do it. Don't waste your time on that, is not unlike rappelling. The more control you have, the less compelling it becomes. Or, a memoir as straight guidebook-detached, evaluative, arranged by area or chronology-is a dry thing.
Still, the writer must never lose the rope entirely. The ramblings of a diary are indecipherable, plotless, sans perspective. Only your little sister wants to break the lock and read that.