THE DIRECTOR'S VISION AND PRODUCTION, AND WHAT WE WANT
First off, being a professional actor is about reading, understanding what you're reading, INTERPRETING what you've read, being able to tell the story honestly, and -- MOST important -- being able to take direction (as well as rejection) from the director. If you can't do ALL these things, this is probably not the field for you
While the audience goes to the theatre to see the film or the play (or turns on the TV to watch the program) as well as the actors who perform in it, it is first and foremost ALWAYS the Director's production ... not the actors'. It's the Director's vision for the film, the play, or the video production that gets seen in its final form before an audience ... and it's why the actor was cast in the first place: because s/he fulfilled the director's vision of the character.
Not all directors believe in or practice collaboration, and depending upon how heavily they may be invested in the production (i.e., if they were hired by the producer for 1 production / film, or if they're a permanent staple with the film company / production company), some are more "hands-on" than others.
Some are more experienced than others and know exactly what they want; while others will allow the actor to experiment a little and try different things. Some are on a tight production schedule (i.e., "time is money"), while others (usually at the college theatre / film or amateur theatre / low budget film levels) have more freedom with their time.
One thing we ALL want, though, are actors who possess the following traits:
1. Superb acting ability
2. Competence. Actors who know what they're doing in front of a camera or on-stage. No director (except those at the educational level) has the time or money to TEACH an actor how to act on set or during rehearsals at the theatre. We'd have no reason to pay such an actor if we have to do their work for them.
3. Experience. Nothing can replace it.
4. Tremendous creativity
5. Readiness. Actors who come to readings and rehearsals prepared, and with ideas ... that they just don't sit around waiting to be told what to do
6. Intelligence and the ability to reason and figure things out on your own
7. A Sixth Sense. We love it when an actor knows exactly what we want before we even tell him / her and delivers it.
8. Flexibility
9. Dependability and reliability
10. A grounded personality and level head