Someone asked, "How can someone prepare for consulting?"
Here's my short answer:
You can look upon consulting as having two parts (for the sake of this answer): subject matter expertise and expertise at offering advice on any subject. Obviously, you prepare tor consulting by becoming an expert in some subject matter—railroads, computers, marriage, divorce, submarines, glass, beer, management, software development, anything at all. Each subject will be different and require a different way to prepare.
The second part, though, has a great deal in common regardless of the subject matter. You need to know how to offer advice that people will listen to and act upon. Over my many decades as a consultant, I’ve frequently been asked about how to do this. So I wrote a book on the subject—and thus became a consultant to other consultants.
The book, The Secrets of Consulting, became so popular that I wrote a second book, More Secrets of Consulting, which also became a valued resource for consultants. So, unless you’d like to hire me as your consultant at $500/hour, and if you’re serious about become a consultant, or a better consultant, I’d suggest you spend the cost of a lunch and buy one or both of these books. Read them, follow their advice, and if it doesn’t help you, ask for and receive your money back. It’s guaranteed.
By the way, the person who asked this question didn't say whether s/he wanted to give or receive consulting. I assumed in my answer that they wanted to offer consulting, but the books work well either way—for consultants or those who hire consultants.