While using the past exams a a rough guide, note which topics were or were not covered in your lectures and required reading. You should ignore the questions in the past exams which cover material not presented in your present course. Use the past exam as a source of practice problems which are at a level suitable for a final exam. Since Club Infinity is not allowed to give out solutions, a good strategy when practicing with the past exam problems is to team up with other individuals in your class, to discuss and compare your answers to the problems. Pay more attention to past exams which were given to classes which were taught by your present professor.
Many professors use their past exams as guides for making new ones.
Do as many practice problems as you can. Make study notes. That is, write out all definitions and theorems emphasized in your course, as well as any tips, suggestions, warnings, or tricks, that your professor or textbook presented. Mark material that your professor said may be on the final exam, and make sure to pay extra attention to that material. Discuss the material with a classmate.