If you long to be an actor, if you have a passion for the arts and wonder about casting, listen to Terry Gross on NPR's Fresh Air as she interviews Director Alexander Payne.
The movie Nebraska is terrific, and I don't just say that because I'm from there (although that makes me a bit biased), but the cast and directing is FANTASTIC.
When Terry asked Mr. Payne about Casting Wil Forte, his answer was so eloquent and to the point. It is an answer every actor should take to heart and understand, to understand how important that first impression really is. Mr Payne explains to Terry Gross,
From the first time I watched his audition tape, I just believed him. What I'm thinking all the time while casting and while directing is do I believe it. When I'm in an audition, I just think oh, do I believe this person. And while directing, after I say action, I kind of mentally wish away the camera and the boom microphone and the technicians, and I pretend I'm just, you know, I'm not looking at a monitor, I'm right by camera, and I'm watching the actors just asking myself do I believe this, if this were really happening.
Listen to the interview. Watch the movie. :)