Just read A Long Way Down by Nick Hornby. What a great book. I laughed out loud in several places, which is something people say a lot but really is quite rare in my experience. He gets dialogue and character just right, and the way these characters bump into one another is fantastic.
This is going to sound odd, but one of my habits is to think about scenarios where characters from really different walks of life get stuck together. It's a framework for thinking about the fiction I might write, I guess, although the truth is when I sit down to write fiction I rarely use any of these imagined scenarios. I guess it's just a mental game I play with myself sometimes. Like, a subway car: what if it stopped and the people in it are stuck together and have to interact, what happens, where do the alliances form, and how would people's perceptions of class and age and race play into the dynamic. But of course there are people who would never take the subway, so that scenario is incomplete. Airports are better, most everyone ends up in an airport sometime in life, but that too isn't perfect. You might never travel; you might have your own plane. Does everyone grocery shop? Maybe we could end up with an interesting mix of people there? But I'm not sure Paris Hilton goes to the grocery store. Not that I want Paris Hilton in my scenario.
Anyway, Nick Hornby has imagined a terrific scenario for getting people with really different lives, educations, and perspectives on the world immediately mixed up in one another's lives. Four people meet on the top of a building in London on New Year's Eve; they're all going to commit suicide by jumping off the top. Without anything to lose or any expectation of consequences, they start off honest (mostly) with one another. And crabby and pissed off. And reasonably sympathetic. Hilarity ensues, although it's not a particularly happy book. It's not a sad book, either. It's a very funny book.
What I like the most about it is the voices of the characters. He gets them very right on. The narration is split four ways, so you have four first-person narrators with really different voices. But each of them relates the action and the dialogue of the other characters and so you get a really round view of all of the four, from their own eyes and from the eyes of the other three. They're consistent. And of course the four characters are about as different as you can get, which makes for crackling dialogue and lots of conflict.
It's a great book. Very quick; it'll take you a day or two. Enjoy.