I have owned a manufacturing and marketing company, a restaurant, and a law firm.

when I was in my 20's I tried my hand at custom made guitars and furniture.

One of the things that life has taught me is that I'm not very good with Joe Q Public. I'd just as soon he'd go die somewhere that I won't have to smell it. As you can imagine I'm not into retail anything. Even my law practice is isolationist. I have an unlisted phone number, I do not have an advert in the yellow pages, I don't hand people my card, I will only take a client if he comes highly recommended and is able to pay his bill up front.

So I guess it was trial and error.

I was very good at things. I was a fine luthier and furniture designer and maker ( I still am it's my hobby). I was a superb manufacturer. But, I despised the morons I had to deal with - you know the kind of people who get all worked up because you won't become their slaves~? Or the kind of person who orders food and doesn't show up to pick it up, or the company whose owners cut the deal to have me serve their employees a daily hot lunch and then the evening before the first delivery, cancels - knowing all the purchases of supplies and the work of preparation was all well underway. Or the purchasing agents who come right the hell out and ask for bribes (some will even tell you exactly what they want) even when you are offering a better product at a better price. Or the owner who wants samples& you give 'em to him then, when you call back to make a deal he smugly tells you there's no need to purchase as you gave him all he needed for free. There are so many ways that people have that take all the joy out of a thing. People like that.

Nope I don't need 'em. I'd rather sue 'em and ruin their year or their decade.

At any rate there were things I was very good at. I have learned to keep 'em to myself. There is nothing that takes all the joy out of a thing quite like making a business out of it.

However if you can handle Joe Q Public and you have a thing you are very good at - and you can figure out how to market it to the population that'll pay the most for it then you are golden.

Don't borrow money to grow or build your business. Don't borrow money to survive.

If you can market to a niche industry you are even better off.

Books are surely hit and miss, but I am willing to bet that if someone can get ONE small workable truism out of any book, then it's worth the few hours that it takes to read them.

When someone does not know much about a subject, how are they to learn about it if not by studying? I'm working on a distillery, and how in the world would I get the first level of understanding without reading about it? The same goes for many subjects, where one has to get the macro view before one can dig into the micro, the minutia.

I've only known one person who used this book to run their business. It was a disaster.
Every book written is a general reference. Every industry has its particular culture. Its important to understand the culture of the industry and to understand and respect the needs of your customers. So any book can give you good advice, so long as you temper it with your experience.