Martin Freeman said something that really stuck with me:
You have to know what play you are in and what your role is in that play. Bilbo [the lead character in The Hobbit] is in a lot of ways the eyes and ears of the audience. He needs to be relatable.As an actor it's your job to know how you fit within the entire story that you are telling. This is true if you are a small or large part. Every character is there for a reason and everything you do as an actor in that role must serve the story as a whole. Plus you have to understand what type of play or movie you are in. Although, the basics of acting by being truthful in imaginary situation are always the same, the way you chose to portray your character can be very different in a broad comedy vs a period drama.
Many actors don't seem to understand that and all they do is learn their own lines, hardly bothering to read anyone else's lines much less reading the scenes that they aren't in.
In the Game of Thrones panel, Michelle Fairley (she plays Catelyn Stark), spoke of the importance of her scripts. She says everything she needs to know is in the script and she reads it over and over again to gleam every bit of information she can from it.
I've gone on a rant before on how annoying I find it when actors say they don't watch TV. But, it can be bad for your career if you don't because if you are auditioning for a television show you really need to know how your character fits in with the show as a whole. Because it is your job to be part of a story that is already being told.
