I only got 45 so there's probably kids on here that are more pro than me, but chrisjb's approach was exactly the same for me. There are many things in legals you MUST know, for example the court hierarchy, and the way to know these concepts back to front without fail is to rote learn them; the lecturer I went to before the exam suggested this approach.
The way I did this was to type up comprehensive notes for each topic (probably 10 pages or so) before each SAC, studied it, and answered all the questions I could find from my teacher or my textbooks etc. Come the end of the year I had a set of great notes for each topic, which I combined to make notes for Unit 3 and 4 to use for exam preparation.
Also, what chrisjb said, just because you know 10 marks of information about a topic, doesn't mean you have to write it all if the question is worth 2 marks. I lost 3 marks for the year on my SACs, all due to running out of time/rushing the last question because I wrote too much. In addition to this, be concise with your answers, and write with some eloquence. Legal Studies is much like Business Management in that respect, having the knowledge does not guarantee you full marks; you need to directly answer the question and write in an orderly and clear fashion.
This will be discussed closer to the exam no doubt, but for the long question (8-10 marks), have a plan as to how you're going to answer it, and know everything you need to include in the answer. This avoids the chance of rambling on in your answer or forgetting a key point.