Note taking is the most common way of doing better. When you take notes, you don't just scribble a few words. You have to capture the key point, or exactly what you want to remember. Don't go into too much detail, only add a few details supporting the main idea of your note. For example, if you were in charms class, you could take note of a certain charm, add the pronunciation, wand movement, willpower, and concentration. The setup should look like this:

Charm:
Pronunciation:
wand movement:
willpower:
concentration:

Another type of note is where you take note of something you fully do not understand. When you do this, you take a sentence from the lesson, and what you think it means , and put it together. This will help you compare, and fully understand the meaning of a word, or sentence.

One thing i would advise you NOT to do, is plagiarize. Take notes to help you on a quiz. Don't copy and paste.