The book breaks down networking in a series of smaller topics - reasons for networking, how to best approach it, figuring out what you have to offer when transitioning roles or careers. It's a compilation of HBR articles which is similar to all the books in this series.
The best piece of advice given was to view yourself as a product and determine what sort of value this product can provide for the industry / company / audience that you seek to appeal to. The book doesn't suggest shamelessly promoting yourself that will leave you looking and sounding like the used car salesman stereotype. However, when you remove yourself from thinking that networking is all about you and more about how you can help the organization and/or people, you will have a better chance of landing opportunities that you desire. At the end of the day, networking is about creating lasting relationships and levels of support where you and your network of people rely on each other in work and sometimes in life.