I did an Inspector Calls so I can give you some tips for that. I remember focusing somewhat on the 7 deadly sins during my exam, whatever the question you can usually include who represents what, the Inspectors speech and Birling's speech are also a very good comparison, with the Inspector using antithesis, rule of three and other techniques while Birling rambles. Pick out the effects they cause on the audience and characters. Compare things like gender and social class, how Sheila and Eric by the end seem to accept their responsibly whereas the older generation, the Birlings, don't. Depending on the question you could discuss who the Inspector is; a collective conscience, a ghost, God, Priestly, etc.
In the exam you should pick out layers of meaning, so take a quote and really analyse it, pick out three or more effects Priestly was trying to achieve, link it to other quotes, etc. Analysing sophisticated techniques also helps, such as antithesis, which is present a lot in the play, through phrases and characters. You could also learn Max Atkinson's 7 points for a good speech and include that if you can. Also always refer back to the question, tangents are good but if they're relavent and as long as you can still address the question.
I did Romeo and Juliet but with Shakespeare, he uses, and pretty much exploits, the figures of rhetoric, which are basically just techniques for persuasive writing. Some ones I know Shakespeare used are antithesis, anadiplosis, polyptoton, etc. Don't get too hung up on these, maybe see if you can find a few in Macbeth and remember them. They're bound to surprise the examiner, as long as they are used correctly.
Also, make sure you know how the exams are marked, look through examiner reports to see where people went wrong and right, and make sure you know the books and chapters well, you'll waste time looking through the book in the exam otherwise.