If this is what you want to do, brace yourself! This method requires a lot of time and money.
The time is not simply that spent on research. Once published, you really need to do a lot of public relations and marketing to achieve sales. This can involve: having a stand on occasion outside bookshops; a web site; speaking on local radio; and having articles printed in the newspaper.
One successful self-publisher has sold 1,000 printed books, in addition to Kindle sales. He has books in bookshops across 5 Australian states. After more than 5 years since the project started, did he expect to get his money back. By comparison, most other self-publishers only sell about 300 books.
There are some things you can do before you begin. See if you can get the advice of several established biographers. Do a course on self-publishing, noting that a memoir is more complex than other self-publishing genres.
When writing the story, there are simple things you can do to make it more readable. For one, weave fiction into the story to embellish the facts and make it more interesting. Also, talk about what was happening in the context of the time, such as who the Prime Minister was. Writing in the present tense also helps make the events seem more real.
Start selling through small and independent bookshops, being sure to support them with public relations and marketing.