I have been a tutor for five years and a teacher for nearly thirty. In that time I have heard all sorts of nonsense talked about the best way to revise for examinations. What I have written below is the real deal - it works!
1. Obtain a good revision guide. Most schools recommend certain ones. Some have an associated workbook of exam questions that correspond to the topics in the various subjects.
2. Plan your revision and begin in good time. If you leave it until the last minute you are making it harder for yourself and are halfway to failing before you have even entered the exam room. Make a list of the topics in your subject then prioritise them. The ones you feel the most unsure about should be at the top.
3. Find a place where you will not be disturbed. A library is good if your bedroom is not suitable. Turn off all radios, ipods, TVs, and computers (If you are not actually using the computer to revise on).
4. Work methodically through the revision guide and try all of the sample questions to test your knowledge.
5. If a topic still does not make sense, go to BBC Bitsize website, read the revision notes and try the questions included.
6. Plan your revision. The golden rule is 'little and often'. This means study a subject for 30-40 minutes maximum, then go and do something else. Come back to it later (or the next day) and continue for another 30-40 minutes. Do not try to 'revise' for hours at a time. You will not learn but you will become discouraged!
7. Stick at it! There are no shortcuts to this, you must be prepared to put in the effort. Just playing at it will not gain you anything. Remember all of this is for you! It's your future.