Try Carl Jung's "Active Imagination" technique.

Create a character in your mind, then have that character ask you questions and write down the back and forth. Don't merely ask yourself questions as you though, really try to act as though someone else is asking you, and respond as you would to another person in a real conversation. Once you've answered, use that character to dig deeper. Have it ask follow-up questions, or questions that you wouldn't normally want to answer.

I began doing this a couple years ago on my own, and only learned later that it was an actual technique that had been around for so long. If you really allow yourself to answer honestly, and really try to put yourself in that character's mindset, you'll be amazed at how much you can discover about yourself. It's essentially creating a muse for yourself that you can access at any time. You may be able to use it to narrow down what it is you want to explore on paper.