From reading countless study guides and books, I have seen particular study methods crop up again and again. These are of the active study nature, which is where you are not simply reading your notes repeatedly, but doing something with the information running through your head - thereby processing them.
You also have to take into account what kind of learner you are. There are tests on the internet to help you discover this, but you can tell what you cope with better whilst you are studying. Some people are better at traditional "book-based" methods whilst others need to hear the information and repeat it aloud, or perhaps see the information presented in some form of diagram or other - thereby being an audial or visual learner.
Once you aquire this knowledge about yourself you can decide what study methods will suit you best. Popular study methods include:
Revision cards: where you cut paper into small cards and write main points about a specific topic on one side, and a question for you to recall the main points on the other. This way you can test yourself when spare moments arise. This is using your time wisely; a skill we must all learn in order to become a successful student.
Spider Diagrams: Place the name of the topic in the centre of an A4 or A3 sheet of paper, enclosed in a circle. Then draw branches from the circle leading to different areas of the page to guide you to a section of the topic. Complete the sheet with all relevant topic headings and brief notes and then when you try to recall this information, picture the mind map in your head.
Mind Map: a kind of development from the spider diagram, as you include colour, pictures and symbols to aid your memory. This does work as the creative and academic sides of your brain are at their best when they work together. You will be better at remembering funny pictures better than a paragraph of words.
I strongly recommend Tony Buzan's books: Use Your Head, Use Your Memory and Master Your Memory as he can explain the above study concepts better than I can. He will also introduce you to other methods such as Mnemonics.
It is a well-known concept that the most successful candidates are those who have good time-management skills. Now let me tell you: I cannot remember the last time I sat an exam fully prepared because I had left enough time in advance to study all relevant information and transfer it to my long term memory. I don't think I ever have, and yet I consistenly achieve good grades. In fact, most of the information that you are revising will not be needed. So now you are thinking: it's just down to luck then, the lucky bandit's just smart. Well, to start, the exams I have sat at this early stage in my life (I'm only 15) have not been terribly hard. I realise that I do need to be better prepared for exams in the future, as I will not get away with it for much longer. In fact, I should have been revising for my prelims today but I didn't do much.
A little pressure can be healthy, and the adrenaline caused by not being 100% prepared can push your memory and you end up triggering recall of things you learned in class. Adrenaline will also carry you thorugh the exam if you did not get much sleep the night before.
You need to prioritise. A good teacher will tell you what things are likely to appear in the exam, and what things candidates struggle with every year. Listen to their advice, different subjects require different techniques and can contradict each other - adapt.
Short, intense periods of revision (say 20, 30 or 40 minutes) are much better than long periods where concentration wavers. And, a really good technique is to review what you have learned before and after each short burst, and then a day later, a week later and so on. This will ensure that the information is transferred to your long term memory.
You have to be interested in what you are studying for it to sink in. It's perfectly possible. If I can gain interest on Physics for the 36 minutes I'm revising it then you can too. Although I have to say, I prefer shopping. That would be a good subject to study.
If you learn to have a real desire to learn and want to gain wisdom ,the information you study will stay with you, just like reading a novel that interests you stays in your mind. It is a skill you can learn with practise. Schools take the fun out of learning, and turn it into a chore. If you teach yourself then you will benefit more. You may not "get" things in class, but get round to revising them at home and it just sinks in. If it doesn't, ask for help. One-on-one teaching is much more effective - no one is there to laugh at you if you answer a question wrong and the teacher will definitely not laugh either, their job is to teach, they want you to succeed!
Study often; make studying a habit. Then it will become enjoyable. Learning things improves your knowledge, wisdom and character as a whole. You will gain new viewpoints and ideas you never thought of before. You will develop as a person and get more out of life.