Reading criticism alongside fiction is a practice I adopted late and regret not adopting earlier. Not book reviews — criticism in the more technical sense: essays that analyze what specific works are doing and how they achieve their effects.

The criticism that has most changed my reading: Roland Barthes on pleasure and reading. Nabokov's lectures on literature (patronizing in places but enormously perceptive on the sentence level). Seamus Heaney's essays on poetry. And James Wood's How Fiction Works, which is the best introduction to the technical vocabulary of prose fiction I've found.

Criticism gives you language for things you already experience. Once you can name what's happening in a sentence, you can notice it more precisely and value it more fully.