Question

What is the best way to focus on a topic of a memoir

Answer 1

Ask yourself questions like who, what, when, where, and why

Answer 2

I would say the correct answer is to ask yourself questions like who, what, when, where, how, and why.
If you focus on these questions, it will be easier for you to stay on track when it comes to what the topic of your memoir is going to be. It is easy to get sidetracked, but if you focus on these questions only, your job will be much easier.