How does the nurse try to assist Juliet and Romeo?
The nurse assists Juliet and Romeo first by introducing them. They each independently ask her who the other is, and she tells them. She tells Romeo that whoever marries Juliet will have “the chinks” (money). Then she serves as a go-between between Romeo and Juliet when they are arranging their marriage. Romeo asks the nurse to tell Juliet to go to Friar Laurence, and gives the nurse a rope ladder that he will use to get up to Juliet’s room.
And stay, good nurse, behind the abbey wall:
Within this hour my man shall be with thee
And bring thee cords made like a tackled stair;
Which to the high top-gallant of my joy
Must be my convoy in the secret night.
Farewell; be trusty, and I'll quit thy pains:
Farewell; commend me to thy mistress. (Act 2, Scene 4)
Even after Romeo is banished, the nurse is of assistance to Juliet in advising on marriage-related matters. She tells Juliet that she is better off marrying Paris, saying “Romeo's a dishclout to him” and she should move on. Juliet does not take her advice. She goes to Friar Laurence, ostensibly to confess, and comes back with a potion to fake her death. She tells the nurse to go away, along with her mother.
When the nurse played matchmaker, she probably did not really expect Romeo and Juliet to get together. Their families were feuding, after all. She didn't even know, exactly, that it was Romeo that Juliet was after at first. Juliet tried to play coy, and she inquired after others too that night. However, the nurse did her part in conveying the marriage message for the young lovers, so she definitely was the go-between. She cared about Juliet, and wanted her to be happy.