Sherlock Holmes had his pipe and Dracula his cape and fangs. My assistant has a friend who only wears short pants regardless of the weather.
Shelly Winters and Marilyn Monroe, who were roommates at the time, went shopping. While in the dressing room, Shelly was practicing a breathy laugh and speaking voice. Marilyn asked her about it and Shelly said she was using it in a scene study class. Marilyn asked if she could have it and the rest, as they say, is history.
As an exercise:
1) Determine what sets your character apart. Think of Angelina Jolie’s lips, Woody Allen’s thick-rimmed glasses, Hitchcock’s girth.
2) Once you figure out what your character’s signature look or behavior is, interview and write a story about how they got it. You will learn interesting details about their past and present.