Best way to memorise quotes?

For the literature exams (GCSE, exam board is WJEC) there are 18 poems, An Inspector Calls, Jekyll and Hyde and a Shakespeare play (for me it is The Merchant of Venice). I'm pretty confident with the content, themes and characters of the books and plays. My issue is with learning quotes, and all of the poems.

Does anyone have any advice about how to best select quotes, especially from the poems? Learning the themes now won't be too hard, but how should I decide what quotes to use? How many quotes should I learn for each poem and story/play? What's the best way of learning them?

Thank you in advance for any help, it is most appreciated,