A the successful people in world don't work hard they work smart and one thing that seperates them from loosers is "they love what they do".
To score good marks in your exams it is essential that you study hard. It may sound cliched, your friends and family would tell you the same but it is not the whole truth. Many students study hard and yet are not able to get desired scores in their exams.
You see, it's not just the time you put in your studies decides the outcomes, it's essentially your performance when it is required. Keeping in mind the exams and the nature of exams is what will help you orient towards your studies. Next, you need to choose a direction in which you want to take your studies and lastly enjoy what you do, when you do it so that it always remains fun for you and you never get bored in your studies.
For general courses that require a lot of reading you can try going through the chapters intensively and use lots of mind maps to familiarize yourself with the concepts. If you know how an idea is being applied in your studies you are in a better position to comprehend and make logical assumptions with regards to it. In case of mathematics and other similar subjects with numerical questions you will need to practice as much as you can. Finally, you will need to focus on the task at hand and keep your eye on the prize, what goals you wish to accomplish should you succeed.
Also, it is important that you avoid procrastination and study with a single minded determination. You can get help from others or make a study group of serious minded students, that may prove to be helpful as well. Try and find sample question papers or old question papers. That will help you prepare for the exams in a more practical way and you will know for certain where you stand with your preparation.