The overview, our mentor M says, should start with a brief hook, "A quote, an event, an idea, a joke, a cartoon, or a statistic--the single most exciting thing you can write about the subject that makes your book sound new, needed, and timely."
Did you get that?
These few sentences are important, so spend time coming up with a great hook--have fun with it! IF YOU ARE EXCITED YOUR READERS WILL FEEL IT. If your book is fun make the hook fun. If your book is informative find a great statistic. If your book is a memoir then, well...I don't know. Let me check with our mentor and get back to you.