How do I prepare effectively for a closed-booked exam?

Although this might seem obvious, my main piece of advice is to know your text really well. Make sure you have read it at least once more in addition to any group reading you might do in class to really familiarise yourself with it.

My favourite way to prepare for the exam was to go through the text and my notes, and group quotes into various themes. This meant that I would have a bank of quotes and ideas already grouped thematically and therefore paragraphing in the exam was much easier! You can add relevent critics quotes and contextual information to be extra prepared! 

Once you feel confident and familiar with your text (and know your quotes really well!), try doing some of the past questions under timed conditions to get used to quickly formulating your ideas when under time pressure. Even if you don't actually write the essay, allow yourself 5-10 minutes to write up a plan as if you were in the exam. This was one of my favourite methods as it was much quicker than spending an hour at a time writing sample essays, and meant I could try more questions.