As a "wait-for-trader", that is, someone who waits for the trade paperback releases of monthly comic books, the Unofficial DC Comics Trade Paperback Timeline has long been my guide through the various DC books that I purchase. The Collected Editions author provides a sensible order to read the stories of this shared universe, often with justification, but without spoiling any of the storylines.
The entire list is separated into "chapters" of the major DC Universe events, with various related books (even if starring different superheroes) grouped together within those major sections.
The various eBook formats (and if you buy the book, you have access to any and all of them; i.e. buying the PDF means you can later still go download the EPUB version) allow you to access the list online or offline on your preferred device. Perfect for those trips to the comic or book store, when you're not sure what you should read next, your device is WiFi-only and there's no hotspot around. And at $0.99, it's so cheap there's no reason to second-guess the purchase. Definitely worth the money.