A good thesis to begin discussion/analysis of the narrator/boy of James Joyce's "Araby" can include the themes of this story since it is the character who is intrinsic to the development of these themes.  Such a thesis can point to the story as one of adolescent maturation by stating that the boy who is the narrator of "Araby" arrives at maturation through a journey of fantasy and disillusionment and a resulting emtional growth.

1. He confuses a romantic crush with religious enthusiasm (e.g. he runs with the "chalice" at the grocery story, the exotic relgious bazaar)
2. The boy never shares his feelings with anyone else and becomes somewhat alienated in his relationship.
3. He experiences emotional growth through this disillusionment and his anger is intensified by his alienation. 

Also, check out the "how-to write a character analysis" at enotes. See the sites below.  There are several excellent pointers.

Writing about the narrator will give you the much to work with since he is the major character. "Araby" is an initiation story in that he loses his illusions and grows up to face a cruel reality by the end of the story.

For your three points, you could discuss him in the beginning, as he reads the priest's books and dreams of romance with Mangan's sister. He is romantic and naive.

Then you could discuss his growing obsession with Araby and what it comes to mean to him. He thinks he can bring romance into his life.

Finally, you could examine his character at the end of the story when he is so disillusioned once he has been to Araby. He is very different from the boy he had been.

Make sure that you state each point clearly in a topic sentence and then explain it. Don't fall into the trap of simply telling the story.

The enotes links below will take you to helpful information about the story and the characters. Good luck with your paper.