Songs have their own mood and feel, and listening to them puts me in the same state of mind. So I have my entire music library categorized into sad songs, angry songs, tense songs, giddy songs, jealous songs--name an emotion, there's a song for it. And before I write a scene I take a minute and figure out which emotion the characters should be experiencing and then run that playlist in the background. You'd be amazed at the difference it makes.
But it goes even deeper than that. Songs also have their own personality, and which ones you like says a lot about who you are. So one of my main character development exercises is to make a playlist for each of my main characters and fill it with songs that they would listen to. It can take quite a while, and usually requires a lot of scouring the iTunes Store and googling song lyrics. But it's worth the effort. I listen to the character's playlist when I'm writing their dialogue, and it always gets them talking on their own.
The only downside of this trick is that I often have to listen to music that I personally can't stand (my music library has a number of embarrassing albums). But it's also gotten me interested in music that's way cooler than I am. In fact, most of my new favorite bands I found because I had to figure out what my two older boys (who are really cool) would like, and I knew it had to be in the Indie-Rock, Alternative, Emo scene--the kind of music I was always a little intimidated by. So I guess it's kind of a give and take situation.
But if you ever hear me blasting Miley Cyrus or the Jonas Brothers please don't judge me. It's a sacrifice for my art--a big one. And if you're ever scrolling through my iTunes and notice that most of my playlists are named after people that don't exist, don't worry--there is a method to my madness. You may not understand it...but trust me, it works.