1. First and foremost, paying attention in class is important. Usually one pays 100% attention to the subjects they like and less for subjects that they don't. Following through, usually, your scores will be higher for the subjects that you like and pay attention to. That's because tutors usually go through the areas which are likely to be examined and prepare you accordingly for the exams as you are paying attention. So the key here is paying attention regardless how you feel about the subject.
2. Complete all your homework by yourself. Try to do as many as you can by yourself before seeking help. This helps to drive in concepts and methods taught in class, and assist you in mastering them well. I have seen people copying homework instead of doing it themselves. These people usually have to put in a much greater effort at the end of the exams to score better, stressing themselves out.
3. Practise even more questions on the same topic. The old adage "practice makes perfect" holds true. With more practice comes more confidence, leading to lesser mental blocks. The speed of doing questions will increase, and the number of careless mistakes will decrease. These are extremely important criteria for you to achieve spectacular exam results. You can do this by using the Ten Year Series, past year prelim papers, assessment books, or even free websites like ExamWorld, which provide some free questions and solutions for students.
4. Learn from other students as well. You can do this by looking at good works that have been marked. Look at the different comments by the teacher, learn the different approaches to answering questions and essays, and understand the common pitfalls to avoid them in the future. Afterall, it's always easier to learn from others mistakes right? I photocopied A grade essays from my classmates to analyse, understand their points, their argument and analysis, etc.
5. Find and discover various ways to check your answers, especially for hard sciences like maths and physics. Looking for your answers and workings again is only one way of checking. Most questions have more than 1 approach (for maths) and by using a different approach and getting the same answer, you are more or less assured of being correct. Other methods can include working backwards to reach what the question wanted to you too. Or perhaps, for probing questions, substituting a value to find that both sides of the equation give you the same results. Or even for physics, by remembering some constants, you can more or less know whether your answer is reasonable a not. An example would be finding the density of oil to be 667 kg per metres cubed. Obviously, oil is less dense than water (1000 kg per metres cube), so the answer was reasonable. This habit is extremely important, and I usually teach my tuition students how to do so and where to look out for such "free marks".
6. Make short notes to read an hour before your exam. Instead of relying on tutors for physics tuition, knowing and understanding the concepts well, memorizing the equations and definitions of the different terms, can suffice in scoring As for your exams. The knowing and understanding the concepts should have been covered in points 1 to 4 above. The equations and definitions on your short paper are mere to there to help refresh your memory so that you do not stumble in exams.
7. Teach other students freely when they ask you for help. If you can explain the question well, it truly means that you have internalised and understood perfectly the concepts being tested in the question. I realised during my JC tuition time that questions other students ask are usually of higher standards than simple questions. By helping them, I trained my mind to be able to solve tougher questions as well. And by being able to explain to them, I became even more confident and sure of myself in those concepts. Take it as a surprise test/revision that occurs frequently.