…is based on what content you put on the back cover of your book.  That’s where most every potential reader goes to determine if your book is a worthy read or not.  Take the time to consider what you want your 15 second commercial to be.  Do you know your audience?  Do you know what they look for when making their selection?  Do you know how to reach them?  Take some time to figure that out.  Only then can you put the right content, right where your potential reader will see it.  Keep it simple, keep it concise, and leave them wanting more.  That more often turns into a sale.