When I have trouble focusing a new project, or even choosing what to write about, these are some questions that help me:
What do I find to be true?
What matters to me?
What subject will not leave me alone?
What character must be heard?
What have I always wanted to say?
What ground have I not covered yet?
Whose voice is speaking to me right now?
If I knew I could only write one more book, what would I want it to be?