An option is to try to understand the subject you're studying by going through its material and once you went through it (understanding means grasping the main concepts, not memorizing lots of details), you will be able to hit the QB. By doing that I usually manage to get around 70% the first time. I then focus on the things I didn't do well and only then I re-do the questions I didn't answer correctly the first time.
After all that you should be able to simulate the exams and get >80% results. This is how I study for the ATPL theory.