There are many excellent books written for musicians of course. I just want to mention two of them right now.
1) The Musicians Way by Gerald Klickstein
This book should be handed out to all undergraduate music students along with their diplomas when they graduate. Or maybe during their junior year. This book is probably most suited to "classical" music performers but I'm sure it's a worthwhile read for all musicians. Mr. Klickstein also runs a fabulous website with many support materials and articles to help musicians navigate their careers. I highly recommend subscribing to his newsletter too. He covers topics such as how to practice, get started in your career, and maintain a musically satisfying career - including how to avoid injury. I can't imagine a better how-to book for the classical musician just starting out in their career.
Gerald Klickstein, is Director of the Music Entrepreneurship & Career Center at the Peabody Institute of The Johns Hopkins University. (He's also an excellent public speaker. I met him at the 2014 Chamber Music America conference when he moderated a panel of concert presenters and artist managers.)
2) Making Your Life as an Artist by Andrew Simonet
This book resonated with me so strongly that I cried while reading the first three chapters. Andrew Simonet is a choreographer and is living the artists' life. He articulates our struggle and reasons for making art so clearly that it makes me completely trust him. So when he hit me over the head with practical and real-world advice about what I need to do to keep on making art, I kept reading carefully. None of his practical advice is new to me. I've heard them many times (manage your time, don't work 24/7, delegate, manage your money, etc.) but this time I think this advice will stick. [I seriously hope so...for my sake.]
Even if your eyes glaze over at the thought of bookkeeping or time management, I hope you read the book for the first 3 chapters. If you're not an artist-type and want to know what it's like to be an artist, you should read this book too.
And the best part: this book is available in paperback and as a FREE e-book. Get it!!