I would try to remember the major characters. Often we remember the characters through their actions. That will help in remembering plot.
Romeo - a lovestruck teen who is implusive. He was in love with one girl then falls in love with Juliet. Gets married but on the same day gets banished for killing his cousin in law. His rash actions lead him back to Verona when he hears his wife's "death". He dies.
Juliet - Another lovestuck teen. Was to be married to someone else but meets Romeo. Is abandoned by the nurse when Juliet and Romeo gets into some major trouble. With Friar Laurence's help, has a solution but it backfires. After discovering her husband's lifeless body, she decides to join him.
Friar Laurence - The man with a plan or two. He has good intentions: wants to end the feud between the families by marrying their only kids and to get Juliet out of a bind. What he didn't see was the what ifs like what if his messenger doesn't reach Romeo before the rumors do. When both teens are discovered in the tomb, he is the one that has to explain to the prince what happened.
Mercutio and Tybalt - Two hot headed cousins that end up dead (thanks to the feud between the Montagues and Capulet respectively) and the reason for Romeo's banishment
Nurse - Juliet's adult influence. Was happy for Juliet when Romeo was good but she withdrew her support when Romeo was banished.