Try improvising in role in a range of different scenarios. If you’re using a script, choose locations or events beyond the play. Learn how your character reacts in a range of different situations. Experiment, and always analyse which reactions, movement, gestures and vocal characteristics work for you.
This is a useful technique. Stand with your eyes closed and ‘see’ the person you are playing in front of you. Picture them in your mind’s eye. Look at how they are standing, their expression, any gestures they make and what they’re wearing. Imagine hearing them speak. When you have a really clear vision of your character, take a step forwards and ‘become’ what you have visualised. You can also use the visualisation technique of looking at your character in a ‘mirror.’