How to Critique Acting. Critiquing any art form is essential to understanding the art itself, and it helps in forming your opinions.
Look at the actors and form opinions about whether you believe the character. Also determine if they are genuinely portraying the character in the right era and setting for the play. This is especially important for period pieces. Pay attention to their mannerisms and determine if they are set in the right era and not too modern.
Listen to inflection. Many actors will have the natural ability to emphasize and inflect the right words in their lines. When you critique acting, listen to those that are seemingly natural, and then turn your attention to those who do not seem genuine. Try to notice what it is they are doing right and what they are doing wrong. This can be anything from volume to their level of intensity throughout the show.
Watch for characterization. When you critique acting, you have to think like an actor. Actors are trained to form valid characters with history, mannerisms and speech patterns all their own. Watch for their choices, and determine if you agree with their intentions and motives for making the choices they make.
Use the right terminology. As you critique acting for an article or paper, make sure you use the proper terms. Understand the difference between stage right and stage left, and know how actors are trained in order to put yourself in the right mindset. Actors are trained in voice, diction, characterization, interaction with the other characters and movement.
Decide if you are moved by the performance. If you find yourself thoroughly enjoying the performance, take a step outside of the acting and look at the individual things the actor does that pulls you in. The really good performances are the best to watch, and they help you critique acting by giving you a gauge as to what to watch for in the future.