You are not alone. 70% of Americans want to write a book. The majority (that's over 35% of Americans) want to write a biography and share their story

Each of us is unique and has lived a life unlike anyone else and has learnt things and had experiences. Some of those are things worth sharing. Things that will help and/or entertain others. Things that might help other people be happier, love themselves more, treat their family better, and many wonderful things

The first thing you have to decide is whether a book is the best way to share your story
Blogging is easier and faster
You can upload videos on Youtube
You can do a podcast or go on the radio
If you choose to share your story via a book do keep in mind that it takes a lot more effort than things like blogging and sharing videos

You still around? I haven't managed to scare you away from writing a book about your life?
Good. Let's get down to the main things

Key Thing #1: Figure out whether you want to entertain OR you want to help people learn from your experiences OR you just want to share a story and let each person take from it what they will
Key Thing #2: Anything below 150 pages won't work. Books below 150 pages are like Documentaries - no one skips Star Wars to see a Documentary on the Dangers Faced by Mushrooms in Large Urban Areas. If you want people to read your biography write a long one
Key Thing #3: If your story must have sex and violence, that's fine. However, with sex and violence you are ruling out everyone under 18 and 50% of those over 18
Key Thing #4: No one cares about your life story until and unless they feel - they will learn something OR it'll capture their interest OR it's entertain them
Basically, you have to write it with the focus on what the reader can get from it
Key Thing #5: It's absolutely critical to polish polish polish your book. You want people to read your story and enjoy it? Make sure you get rid of all the typographical errors and grammatical mistakes. If possible, get an editor and have it refined and polished until your life story shines
After you have your book ready, here are a few tips on how to get some traction

#1 - Promote the book to readers looking for Biographies and Memoirs. Most of the promotion avenues are geared towards Fiction readers. You will have to carefully check your book is being promoted to Non Fiction readers, and in particular to those looking for Biographies and Memoirs
#2 - Make sure it is being promoted to readers who geographically and culturally match your book. If your book is about growing up a Boomer then a promotion venue focused on Millenials in Europe isn't going to get you any traction
#3 - It's a marathon, not a sprint. Don't spend all your energy at the start and get frustrated. Don't spent all your money at the start and run out of budget. Spend as slowly as possible - until you find a marketing venue that works
#4 - Do not buy 1000 copies of your hardcover for $20,000
#5 - Do not buy any marketing packages for $25,000. In fact, don't buy any marketing packages for more than $100 or $200 until and unless your book starts selling well

When writing your biography you'll have to be patient and take the time to craft your story well and polish your writing
When it's done and you're dying to share it with your future readers, you'll have to be even more patient. A biography writer and his money are soon parted - unless the biography writer proceeds extremely slowly and keeps his chequebook and wallet tucked firmly away