First, read the following essay by David Eggers, author of What Is the What:
http://valentinoachakdeng.org/essay.php
This will help give you some context for the novel and an understanding of how it straddles the fiction/non-fiction world.
After you have done that, think for a moment about Valentino's journey & consider the journeys of other characters you have read about before (e.g. Odysseus). How does Valentino's journey compare? Is he on the "hero's journey" as other characters in literature have been? If not, where does his journey differ in significant ways?