Acting is an occupation of Make Believe.
This means putting yourself in a fictional role, such as film, drama and television.
To be a good actor or actress you must put yourself in the character you are playing. Which is to say, if you are acting as a mad or insane person, you have to believe that you are mad or insane to be able to bring out a rewarding outcome.
A good actor must have:
1. facial expression.
2. body language.
3. Ability to read and understand your script or role.
4. A good actress must be good in communication etc.