The phrase "closed book exam" is enough to make even the most seasoned English Literature student shudder slightly. It's a concept that can set students into a complete panic, keeping them up all night as they frantically try and cram Shakespeare into their brain - and so my first tip is to breathe and break everything down. By taking your text and breaking it into bite sized chunks, everything becomes a lot clearer and simpler. Instead of sifting through hundreds of pages of information, hoping some of it will stick, you need to actively seek out the exact moments you can use in the exam, and focus on committing those to memory.
This is easiest to do with plays as the act structure already gives you a vague set up for sections; for example, the five acts of Shakespeare's As You Like It fall neatly into five sections. Similarly, in poetry you can take it poem by poem or even poet by poet if you are particularly crunched for time and need an even broader overview. If you find yourself with a novel without a clear chapter system - or an uneven, bulky chapter system - I would recommend pinpointing high points in the narrative, moments of change or where significant themes crop up. This means that you will remember your decided structure far more easily.
Once your narrative is split into these pieces, and let's take As You Like It as an example, you should go about providing a brief overview of the plot and themes from that act - I recommend using a large sheet of paper that you split into three sections to record all this information initially, but there’s no wrong way to go about writing all this down! So, to summarise Act One of As You Like It, you might touch on the introduction of Oliver and Orlando as warring brothers, highlighting Oliver's villainy and Orlando's sweetness, and how Shakespeare seems to deliberate juxtapose that with the devoted cousins Rosalind and Celia, continuing through the whole act and noting any plot point you deem to be of vital importance. When noting the themes of what you are studying, it is important to tailor it to the topic that the exam board asks you to focus on - if you are studying the pastoral elements of As You Like It, when running through the themes in the first act you will want to focus more on the villainy of court being summarised in Oliver’s cruelty toward his brother, and Rosalind’s misery at the unlawful banishment of her Father, for instance. Keep your notes focussed on exactly what you are studying and you will find selecting quotations much easier!
Once you have a strong grasp of what this section is truly about, the themes that run through it as well as the overarching plot, you can start selecting quotes to summarise any points you might make. For example, AQA currently focuses on the pastoral when it comes to As You Like It, so the quotes you would select that would perhaps illustrate themes based on the dichotomy between the city and the countryside. I would recommend picking as many as you feel comfortable with learning, but a good base line is five. If you learn five quotes from each of the five acts, you suddenly know twenty five quotes from the whole play, which seems like more than enough to be getting on with for an essay. Quotes such as “they fleet the time carelessly as they did in the golden world", or "to liberty and not to banishment" would best play into a pastoral essay, and so the focus should be on remembering these moments - there's no point poring over two dense pages of word play between Rosalind and Celia if it will prove irrelevant in the exam!
Once all of this is recorded on your large sheet of paper/whatever method you feel most comfortable with, it’s time to turn your findings into your preferred method of learning. Personally, I recorded my quotes from each section onto my phone, and would listen to them on the bus, whilst I was brushing my teeth, when I was falling asleep, any chance I got. Listening to them over and over was the best way to get them into my head. For other people, writing each quote onto a flashcard and carrying them around with you to occasionally test yourself on is a good method, or even using them as practically as possible, setting out to write essays with the set of quotes that you have, the act of using them in the same way you will in the exam proving instrumental. For some, even the act of hanging the sheet you have already made on a bedroom wall will be enough to stick them in your head, as you look at it everyday.
The final step would be to test yourself to write essays with less and less help around you. First, banish the entirety of the text completely - who has time to flick through dense dialogue in an hour long essay? - and just have your list of selected quotes. As you begin to learn them and grow increasingly comfortable in certain aspects, remove them from your list and only have what you struggle with in front of you. Finally, get to the point where you don’t need any quotes to prompt you in a practice essay, safe in the knowledge that it is all stored neatly in your brain! Hopefully, all of this will keep your revision succinct, focussed and successful!