For a quarter century now, I've hosted a radio show and written for major media outlets, mainly about career issues. As a result, publishers have sent me literally thousands of self-help books. I have scanned, skimmed, or read most of them.
Publishers keep publishing them even though they rarely say much that's new and important. Instead, usually:
So what's a person to do?
So what's my recommendation to people who want to grow professionally and/or personally?
1. Start with Hey-Joe School. Whatever questions you have, ask "Joe,:" someone in your workplace or a friend. That yields you just-in-time learning, with answers provided by someone who knows you and/or can answer in light of the specific context. Plus, it's free.
2. Google your question du jour. The top-listed search results are the most often linked-to and thus have been proven useful to many people. Odds are that one or more of the top three search results will give you the information you need—usually in an article and, unlike a book, it's more likely up-to-date. And it too is free.
3. I'm certainly not anti-book but believe that reading just these eight classic how-to books will give you the biggest bang for your self-development time:
How to Win Friends and Influence People
The Feeling Good Handbook
What Color is Your Parachute?
Good to Great
How to Stop Worrying and Start Living
And if I may be allowed the hubris of recommending one of my books:
How to Do Life: What They Didn't Teach You in School.
I also encourage you to look for books on your specific career. Often particularly useful is a book that consists of a chapter written by a different practitioner in the field. For example, The Call of Nursing: Stories from the Front Lines of Health Care, consists of 23 varied nurses' candid self-reports of what their career is like.
4. Beyond those books, which most people will find worth reading cover-to-cover, I recommend reading the Amazon reader reviews of any other books that strike you as potentially interesting. Those reviews are listed in order: from most to least helpful to other readers. Usually, a book's major ideas are presented in the first few reviews. If reading those reviews makes you lust for more, then, good, buy that book. But before you decide to read it cover-to-cover, start by reading the summary chapter. It's usually the first or last one. That often is all that's time-effective to read. Still want more? Then skim one or more other chapters. Still want more? Then, of course, read those chapters or even the entire book.
5. Finally, outside the self-help genre, if you enjoy reading, a biography can be both instructive and inspiring. Here are some modern classics:
The Bully Pulpit by Doris Kearns Goodwin
The Last Lion by William Manchester
Autobiography by Moandas Gandhi
Eleanor Roosevelt by J. William Youngs
Wrapped in Rainbows by Lisa Boyd
Thomas Jefferson by Jon Meacham.
I.M Pei by Jill Rubulcaba
John Adams by David McCullough
Benjamin Franklin by Walter Isaacson
Lincoln by David Herbert Donald
Marty Nemko's bio is in Wikipedia.