1) I ask the student about his course to see if he understood it well, and if he did not understand it I explain it to him with as much detail as I can. And you memorize your lesson thanks to a deep understanding, and thanks to super fun mnemonic tricks ;) 2 ) The exercises are taken from the textbooks that the student has. These are the exercises that the student has already tried to solve, but without success. 3 ) Finally, I give him writing advice to maximize the gain of points during his future checks/exams. I am persistent, curious and rigorous. My students and my friends say that I explain well, but that's up to you to judge.