I don't take notes, typically. Nor do I highlight. But I look up every single word that I don't know. And I frequently look up the etymologies of words as well. This practice has improved my vocabulary immeasurably. Also, I concentrate when I read so that I comprehend what I am reading. Sometimes I will catch myself scanning without internalizing. I will then reread what I glossed over so I capture the meaning of the sentence or paragraph.