When I use humor in my work, I try to do what David Sedaris does. If you ever read any of his stuff, he is always super funny right before he says the thing. I think this makes the emotional drop more dramatic.
I recently heard from a student of mine who's El Salvadorian, and she told me she finally understood the book's title story now that she's been away at college for a year. Most of the response has been geared toward the book's approach to class issues, its treatment of Miami as a landscape, and the way the characters handle their budding sense of what it means to grow up as "other" in the U.S. while still seeing it as home.