I agree with that advice up to a point. It's definitely a good idea to know what is being published and is successful, has been monetarily successful or critically successful, is in demand, etc. What is currently going on. It is also good to find books and writers you admire and would like to emulate and ones you would prefer not to emulate.
However, if you really want to improve your writing and develop your own voice simply reading is not good enough. You have to read like a writer. You can be extremely well read, having consumed a large mass of noteworthy books and not know a thing about writing, or even better: good writing. Read a lot of literary critiques, especially by people who don’t write books themselves and you will see some really bad writing. Professional critics are some of the most prolific readers and the worst writers imaginable.
So what is reading like a writer? When a reader reads a book they fall into a kind of trance and forget themselves, and their lives and that they are even reading. It's like being in a dream. This is by design and if it doesn’t happen or is on and off, the book is flawed. If the reader starts thinking about what’s for dinner or skips pages to get to the good parts, the book is not doing its job. Certainly there are some books that “break the 4th wall” and take the reader out of the story, probably for some philosophical detour, but if that detour isn’t also all-consuming, then the book is failing in doing its job.
However, as a writer you can’t learn anything while you are in the trance of reading. All you can do is enjoy the experience. As a writer you need to read any book you read for expanding your writing chops, more than once. In fact possibly, probably many times. The first reading should be strictly as a reader; for pure enjoyment or lack of. After you have read the book, you need to note your gut reactions. And hopefully on a more specific level than it was great, ok, or bad. What parts were really enjoyable and what about them made it enjoyable for you. And the reverse; what was bad, boring, dumb, cringe worthy and why.
At this point the writer/reader has to decide: am I going to treat this book as a writing learning experience for myself or not. If yes proceed to reading the book as a writer, if not? go on to another book.
At this point the reading becomes a research project. You are going to analyze this book and figure out how it works. You may read the book many times for different purposes. When making a pass through the book, you may read the whole book or just specific chapters.
Firstly, you want to read the book slowly, resisting the pull of the book to put you into a trance and remain conscious of the effect the book is having on you. Did you come upon a sentence or a paragraph that you particularly enjoy or admire? Stop. Ask yourself why? Was it the wordsmithing, or the psychological insight, the unexpected plot twist, or the fabulous dialogue? Likewise, where the book falls short, ask yourself why? What is lacking? You may want to take notes. After re-reading the book or parts of the book in this way summarize your responses. What made this book above average or below average for you? What parts(types of writing) does the author do wonderful work and what parts could use improvement? And what is your response/preference? Are you particularly wowed by great dialogue or killer descriptions? Where does your interest(s) lie?
At this point if you have found parts/paragraphs of writing you particularly admire, copy them out and keep them to refer to. I keep a file(s) of writing samples I admire and often look at them before I start a writing session or while I am writing. And I am not the only one who does this. Famous writers do this also. Quite a while back I read an article in Writers Digest where some famous (don’t recall the names now, one of them might have been either Margaret Atwood or Joan Didion) authors did this practice.
You can also practice a drill; writing in the same way the paragraph was written. Take the piece of writing and make similar a piece of your own by replacing each word with a different word of the same type. For instance the sentence:
James took a pie over to his aunt’s house.
Would become:
Harriet broke the cup from her mother’s collection.
You can be a little lenient with the prepositions.
Often the whole is greater than its parts: it’s not the word or sentence but the way several sentences come together in a paragraph. Doing drills like this can be very helpful because they take you out of viewing something from the outside to creating it from the inside. You begin to feel the relationship of the writer to their words. Instead of just writing a whole new book, doing drills on areas you need improvement on can be more helpful. That's what elite athletes do and top musicians. They don't just practice playing matches and performances, they work on specific areas that need improvement.
Another way you may want to read the book is noticing the different parts of writing (description, dialogue, action, internal thoughts, and narration) the author uses and how they use them. Which does the author use most often, which least often or barely? Which does the author do well and what not so well? How does the author combine the different parts? Each author has parts they are better at than others and each author has their own way of weaving together the different parts.
You don't have to only analyse books you think are spectacular on all levels. You may like one writer's descriptions and another's plotting. You may love one writer's dialogue and hate their action sequences. It's helpful to clearly understand what you admire and why and what you find lacking and why. And then look at your own writing and ask yourself what you want it to be. What you want to improve and in what way.
Reading a book as a writer doesn’t only help you technically but it helps you develop your own aesthetic. Writing isn’t just technique. It's what you want to say in the broadest sense. What do you want to show the reader? Do you want to show the reader how brutal and vicious the death penalty is? Or how full of mystery, beauty and magic the world is? Or how people are able to change the whole way they operate in the world? Or how entrancing a great romance is? You may not even know yourself until you see what you want your writing to be in how others write. Until you say, "I want to be able to do that."
What is this author doing? Pay attention. Be specific. Do I like or loathe it or simply not care? How do they do it? Do I want to be able to do it? Do I want to avoid doing it?
