There is no magic bullet to learning, and many people have been poorly served by being convinced that learning should be easy. No, it shouldn’t be. When you are learning difficult material, it can and should be a challenge. It it was easy, anyone could do it and your specialized knowledge would have little value. The answer is the same as it is for any other test: study hard, know the material, get a good night’s sleep before the test, don’t drink the night before the test, don’t drink the day of the test, and try to relax when you are actually testing.