I try to read at least 16 books a year (usually it turns out to be more). I cannot stress enough how much this helped me increase my skills.

One example: The Go Programming Language. I tried using Go several years back after using Java for years and my experience was horrible. Then I read this book and I understood the philosophy behind Go, followed all exercises. Am I Go expert? Far from it. But I am proficient enough to write my own tools or contribute small fixes to other teams at work efficiently.