how to cram revision?Watch
Make sure you have the plot, characters and themes down.
Maybe watch a production of Macbeth or A Christmas Carol.
Memorise only key quotes that are adaptable to different themes and characters. For example in Macbeth, choose a quote that suits a character and a theme, and another that chooses another character and another theme etc.
Perhaps read summary information on each theme (found online) and check out SparkNotes for Macbeth - it’ll dumb everything down and make it seem easier to read.