This book is at least a decade behind the times, unless you really need advice on how to professionally organize your WordStar folders in MS-DOS, or download textfiles from CompuServe.
With that said: if you are prepared to ignore half the book, the rest is certainly worth the trip. Oh, well, no, you're not going to be able to read the book & instantly be transformed into a freelance editor & contract writer. But it has excellent advice on how to present yourself to potential clients, what to consider as far as your target market, and even hints as to when you want to "fire" (or avoid) a client.
Not an ending point, but a good place from which to start. There are very few books on editing & writing as a business.
Now if only someone would rewrite this book for the Internet age....