Another point you might make is the fact at the beginning of the novel the narrator does not see the reality of his surroundings as the reader does. At the beginning of the story, he is a boy who plays in the streets as night falls:
The cold air stung us and we played till our bodies glowed.
He is oblivious to the "muddy lanes" and garden odors.
Mangan's sister, like the child's play, provides another escape from reality. The image of her that he carries to the market place makes him ignore the
flaring streets, jostled by drunken men and bargaining women
At the end of the story, the boy sees the reality of the fair for what it is--cheap, desolate, and tawdry. He sees himself as foolish and vain, and he recognizes that his attempts to win the affections of Mangan's sister are in vain.
Well, one place to start would be to think through how the boy is compared at the beginning of the story and what happens to him at the end of the story when he experiences his epiphany and becomes a lot more mature. This will allow you to compare and contrast how the narrator is developed in the story and crucially how the experience of going to Araby initiates his process of maturing.
It is clear from the beginning of the story that the boy is youthful, impossibly romantic and idealistic. He views what Mangan's sister has asked him to do as a romantic quest with himself as the knight in shining armour:
These noises converged in a single sensation of life for me: I imagined that I bore my chalice safely through a throng of foes. Her name sprang to my lips at moments in strange prayers and praises which I myself did not understand.
However, this highly romantic view of his life and his relationship with Mangan's sister is destroyed by the reality of the bazaar and the darkness that surrounds him at the story's close:
Gazing up into the darkness I saw myself as a creature driven and derided by vanity; and my eyes burned with anguish and anger.
He has realised the falsity of his illusions and is ashamed with how he had looked on life, and now is a maturer individual after his epiphany.