If your life was marked by an illness, whether your own or that of a parent or spouse, write about the origins of that health problem. You can write about a genetically transmitted disease by looking at how it has affected your family tree, and how different eras offered different ways of diagnosing and treating the health imbalance. You could use the lens of family medical history to write an autobiography as family saga against the backdrop of monetary concerns, immigration and various socioeconomic issues.
If you have a strong interest in astrology, write your life history from the perspective of different planetary transits. You might want to begin before your own birth and talk about the alignment of the planets in the sky at the moment of your parents' first meeting. You could discuss how your birth chart contains echoes of your parents' charts and the ways in which those charts describe your early home environment.
Dispense with the idea of a linear narrative and write an impressionistic biography of yourself. For example, a writer who possesses both an interest in chemistry and a poetic bent can compose a unique autobiography combining these two elements. Write a series of poems or short prose vignettes comparing different people, adventures, places and periods in your life to the elements of this chart.
Write the story of your life in terms of different songs, films, paintings or books which influenced key events. If your parents have told you that you were conceived as a particular song played in the background, include that. If you made a key decision about what career to pursue after reading a certain book write a chapter which begins with that literary work. Write about the movie you went to with a date the night you realized that person was the love of your life.
Weed out the "boring details" Dahl referenced by perceiving the landscape of your life in the form of a myth or fairy tale. Write a story which conveys the emotional reality of your life. You might want to include interfering deities as in "The Iliad" by Homer. Or you can write about conflicts and challenges you experienced in terms of giants and magic spells masking the truth. If you have a talent for drawing or painting, you can illustrate your life story as either a children's book or graphic novel.