I go to lectures and take some notes, but don't obsess over getting everything down on the page. This is more just important for being the first exposure to the content. In a few days I go to read the pertinent material that was covered in the lecture and take detailed notes. This is the second exposure, and material is already starting to cement in my mind from the lecture now. Then make some flash cards and repeat the notes to myself aloud until I remember the bits that I didn't initially.