I know reading has become less prevalent among the younger generation as there are just so many other options including television, podcasts, websites, social media, and on and on, but there are a lot of great books out there that can really help your tennis game.
I just started to reread Winning Ugly by Brad Gilbert. Even though Brad played mainly in the 1980's and early 1990's, the content of this book is still relevant and can be invaluable to players of all ages. One of the first sport psychology books, The Inner Game of Tennis by Timothy Gallwey, is a great simple guide to how you should think on the tennis court. Tom Brady, the best quarterback of all time (in most people's opinion), has attributed a lot of his success to reading and following the ideas in this book.
Allen Fox, who wrote If I'm the Better Player Why Can't I Win?, puts forth some valuable thoughts which can easily be transferred to a player's ideas and strategies on the court. My brother, Paul, wrote a book called Coaching For Life, that gives some great insight into being a player and a coach on the ATP Tour (make sure you read Chapter 18 about "My Brother the Coach").
There are countless books, documents, and manuals that are published by the USTA, USPTA, PTR, Tennis Industry Association, and even Tennis Magazine, that should be a part of every player's assets when stepping on the court. Try to find something that makes sense to you and challenge yourself to execute it in practice and in your matches. People's experiences coaching and playing tennis can become part of your preparation to solve the puzzle that is put in front of you each time you step on the court to play a tennis match.
Steve Annacone, USPTA Elite Pro, is the Director of Annacone Tennis, www.annaconetennis.com and MyHamptonsPro, www.myhamptonspro.com in East Hampton, NY . Steve is also a tennis professional at Ventana Golf and Country Club in Tucson, AZ. In addition, Steve and Miguel Coelho have introduced the JET (Junior Elite Tennis) program at the Tucson Jewish Community Center for high level players ages 8-18. Please contact Steve at firstname.lastname@example.org