Along with Adam Anderson, I co-wrote a prep book for the Physics GRE, “Conquering the Physics GRE.” The revised Third Edition is published by Cambridge University Press and available on Amazon as well as brick-and-mortar bookstores. Our website has errata sheets and some other useful information.
Below, you can find a webinar I gave for the American Physical Society with some tips for GRE preparation. You can also find an article where Adam and I were interviewed about the physics GRE here.