Earlier quoted context omitted.
For freelancers who want to improve (it was my case years ago), the best book is "The Secrets of Consulting", by Gerald Weinberg. https://www.goodreads.com/book/show/566213.The_Secrets_of_Co...
Thank you for making me aware of this author. I see he has several books on topics I find valuable.
If you like "The Secrets of Consulting", the next one for you should be "Exploring requirements: quality before design", by Gause & Weinberg. What an eye opener it was for me!