The most important thing to know about location sound isn't how to push buttons and faders, or really even how to use recorders. The single most important thing to know is how to use a microphone. If you don't know what various mics should sound like, in various conditions, it doesn't matter how you record it or what track it's on or what the level is, it will be bad.
The best thing I could recommend is to get paid to learn. Go and be a boom op first. Learn to know what you are hearing and how to use various mics in various conditions, optimum or horrible. Simply reading will not train your ears or you ability to make decisions and choices on the fly. Learn what it takes to be a good boom op. How to solve the puzzle that is each shot and how to dance with the talent and crew when Action is called.
On set recording is dealing with pressure and troubleshooting. How can you get that mic where it needs to be and around all the lights, stands, the dolly, the focus puller, the gripology, dealing with a horrible location, in advance. You will want the Locations people and the cinematographer to be your best friends. A book won't tell you how to charm a cinematographer who wants to light your boom op off the set.