Actor convince yourself something is real. Controlled obsession , say it is real, it is real. Vibrate with feeling. Actor has to train his or her ear, behavior that the characters are feeling. Actor look into special interesting things of the character.
Actors discover things coming out of character.
Take practical advice from directors , etc. You must try to look good for camera. Learn how not to lose the audience if you're the protagonist. Back of mind understand camera. For a good performance , do things minimal and very, very quietly.