Hello, the key to succeeding in your GCE Exam will be paying attentive minds to your teacher during classes.
Beside that, you will have to draw a good reading time table and stick with it.
Alson avoid studying alone for what you belief correct might just be wrong.
While studying, always make sure to treat some past exam questions for they can give you a hint on the frequently covred sections of the subject in question.
Past question papers will also help you prepare your mindset for exams as by frequently treating them you become more familiar with similar questions.