Put it on flashcards. Or rather, write in longhand with a pen or pencil your important notes. The act of writing it out embeds it deeper in your memory than reading or typing it. You don't have to use the flash cards, though they can help you identify the areas you need to focus on, i.e. read it and write it again. Or sing it, or recite it while dancing.

Math, you just have to keep practicing. Find more problems online to practice, do it on paper with a pencil.