Every single day and night, you can explore Hogwarts' Classrooms. In those classrooms are desks which can be opened and examined for items inside. In some classrooms, a desk will not open. In others, some desks will have nothing inside. But in every classroom, there can be found AT LEAST one wizard card and AT LEAST 4+ beans. These cards and beans regenerate as different flavors and cards and allow you to consistently get different cards and tons of beans. If you explore every classroom day and night, without acheiving any other cards anywhere in the game, by Night 4, you should easily have all 101 witches and wizard cards, even Albus Dumbledore. I had mine by Day 3, and soon found myself trying to Triples of every card, which I achieved.