At the end of each chapter, there is a great deal of suspense that whets the appetite for the possible outcome in the next chapter. Each time something unexpected (or not) takes place just at the right time, thus, providing these many mini-climaxes. Quite honestly, this is what kept me interested because I got a bit irritated sometimes--maybe it was Katniss; she reminded me of an ex girlfriend of mine; a lot of potential in her skills and abilities, but, at times, a bit of a loose cannon in word and deed.
Collins uses humor or maybe call it black humor, when she describes the characters of Haymitch Abernathy, their drunken supervisor, and Effie Trinket, the woman who calls out the names drawn to be tributes. Both of them act with less than regard for their charges, appearing rather silly in their first appearances. Humor is also used with the three finger salute which is a silent answer to the power of the government and yet is an insult also. The last black humor which appeals to me is Katniss forcing the game master to change the rules of the game to accommodate her threats of suicide where all of the tributes would die and no parades could be held. Collins uses humor to show the hypocritical actions of the government and its agents.
Collins uses flashback throughout The Hunger Games to develop her characterization of Katniss. Since the story is told through first person point-of-view, most of the flashbacks occur either through Katniss' memories, like when she thinks back to the time she first met Gale, or as she retells a story to another character, such as when she tells Peeta the story of how she got Prim her birthday goat.
By using flashback, the author can time exactly when she wants to reveal certain facets of the character's past. The reader may wonder, 'why is she like that, or what happened to her?' and the flashback allows the author to address those concerns, even in the middle of all the action.