Part 1: On a blank piece of paper, start a freeform list of words that you feel relate to your work. They can be adjectives that describe the mood you are going for (like "dark" "uplifting" etc), or thematic subjects/statements (like "death" or "money doesn't heal the heart") or central conflicts ("Harry vs. his preconceived notions of love") or even just colors, feelings, objects of importance -- what ever comes to mind.
Part 2: Once you have a list of thirty or so words and statements, take another piece of paper and draw a large circle. Start placing your words in and around the circle in the following manner: Words that you feel are more important, of greater significance, and more central to your particular piece, place closer to the center. Remember, a circle only has one true center -- what will occupy this space!
Part 3: Write a short piece about a recurring dream or neightmare the character has. This will not only help flesh out your story, but help flesh out your character and his motivations as well.
Part 4: Write an emotionally charged childhood memory of the character. This can have nothing to do with your story, or it can be interwoven into it, whichever feels most comfortable to you.