Finding a "voice" for your characters

It's been busy around the Reynolds home, and on top of that the kids and I were sick last week. I'm finding that juggling a bunch of different writing projects is... well, difficult. I'm still incorporating feedback into the MS I have out for querying, working on preparing for NaNoWriMo '13, and also trying to help others with critiques.
After finishing the outline of my new novel, I decided that one last thing that I wanted to do before November was work on my characters' voices. I'm trying to figure out their unique worldviews NOW, before I start writing them, because voice can be a very difficult thing to put into a manuscript after it is already written.
I came up with several "prompts" for each of my characters, such as "Why did you decide to take this career path?" "How do you feel about your siblings?" "What's you favorite TV show?". Then I started responding to the questions as if my character was answering. It's been helping me a lot with character development, and getting everyone's unique voice straightened out. I highly recommend trying it out before November!