Bad actor knows all 'lines' and says them plainly plain, samely same.... Lifeless words without a 'soul.' In the end, it can't look like acting... Audience is interested in body language, movements and and behavior, not just words or information. During rehearsal try this with a scene partner: have emotion,soul, and kind of understanding or objective of the script. Don't just read your line. Feel it. feel it good. This will help you come up with behavior for the characters in the story.