Early on in my career as a professional artist, these three books were so helpful. I began in the pre-digital era so it wasn't very easy to find information about the business of art and, even though there is more information available now, I still find these three more valuable.
Taking the Leap-Cay Lang: This one is filled with information and examples of everything an artist needs to create a professional portfolio, from writing a curriculum vitae, to an artist's statement, and more. The author even discusses how to connect with galleries. These were all the things I never learned in art school but what I needed. After sending out my first 6 submissions to galleries, I was contacted for interviews by 5 of them and immediately got a solo show that ended up on television and in print. That was amazing!
The Creative Habit- Twyla Tharp: This one is an inspirational read. Choreographer Twyla Tharp discusses how she comes up with ideas and then actually follows through on those ideas. It is a book that I return to over and over for inspiration.
Writing Down the Bones-Natalie Goldberg: This one was incredible for information on how to write anything. When I stumbled upon this tiny edition I was so happy as I could carry it around in my purse. I spent a lot of time in the dental office with my daughter (braces) so I could pull it out and read it anytime. It really helped me to not be intimidated by writing but to actually look forward to it.
So, though these three don't all have something directly related to the career of a painter, they were all wonderful resources.