This book came very well-reviewed, but I found it disappointing. It really should be titled 'what do young people wear'---which is something different from how to look young! In fact the women who remain most attractive (like those I see around me here in France) often do so by shrewdly avoiding wearing things that are really only successful on young bodies; wearing 'young' clothes that don't flatter actually makes you look older, and maybe just a little bit sad. But that's pretty much the message of this book: wear these sixteen items of clothing that young people wear---whether they look good on you or not.
It won't fool anyone.
A much better book for looking sexy and attractive after 40 is Staging Your Comeback by Christopher Hopkins, which includes not only practical and realistic advice on clothes, hair, makeup etc, but shows pictures of real women who have really been transformed by intelligent and beautiful clothes and makeup.