Whether acting in an audition, on set, or in class, a real person is always in front of you.
So, there’s no need to pretend.
Try to catch their attention.
It won’t be easy to attract the attention of a famous actor; in an audition the reader will usually have their head down, so getting him to lift his eyes will be a challenge; your fellow actor in a scene might be nervous and have ‘The plexis up.’- eyes are glazed over, locked in position. That will make it hard to reach her.
Your fight to reach any actor in front of you is immediate.
Can you get the other actor to blink, blush, smile, hesitate, or give a tell, as you send your line? What is there about the other actor that you like and more importantly what is there that you don’t like?
The difficulty in trying to reach the actual person in front of you is everything. – puts you right where you want to be - in the hot seat.
The camera loves that.