In contrast to an ordinary No which begins with No and ends with No, a positive No begins with Yes  and ends with Yes.    The Power of a Positive No:  How to say No and still get to Yes by William Ury    

Life, she’s a complicated–and never more so than when you have to say No in a situation which expects a Yes.  This book outlines how to do that in a simple, straightforward way.  This is a quick and enjoyable read (I read the  book in an afternoon) but the strategy proposed is anything but.  However, I am with the author in believing this approach is worth it in the long run.  The benefits outweigh the costs in economist speak. The main point the author makes over and over is that the harder the No the more respect you have to give to the person receiving that No.  I was particularly struck by the quote by Frank Barron at the beginning of Chapter 3  (Respect your way to Yes). “Never take a person’s dignity:  it is worth everything to them, and nothing to you.”