Basically for me, I actually crammed for Legal Studies. It was the subject I spent the least effort and time on. My effort got me an 89, surprisingly.
Anyhow, what I did was read the textbook (I used the Cambridge one, never bothered with Pearson), look at questions from dotpoint, do a few past papers, do a bit of readings every now and then. During exams, when preparing essays, write notes and think of the possible questions they will ask you (they come from the themes and challenges section). So that's how I got my mark.
And to tell you, I never properly studied for World order because it was so linked with human rights and crime. All I did was prepare notes and think about questions they'd ask you.