cramming is great if u have the memory for it. otherwise, consistent study is important. but don't bother trying to remember everything. u should be more concerned about understanding concepts and processes, and just going through wot u've learnt. focus on areas that are giving u trouble so u don't have to worry bout them as much before exams. i'd say consistent study is the key, maybe 3-4 hrs a week on each subject, depending on how strong u r, ur level of interest etc. its no good spending 30hrs one week studying, and none the next.