As an actor you need to be in total control at all times. You need to understand what are the elements of yourself that you need to change and modify so that you can clearly communicate your choices. For that is what acting is: Communication. A lot of people might not know that, but it is true. Your job as an actor is to communicate, however when you act your habits maybe present. If so, then there are things being communicated to the audience that you are not aware of. Some common examples are head flicks, speaking up at the end of a line, pursing your lips, standing in a way that is too casual for the character you are playing. These are just a couple of example of not being in control. If you are trying to be a powerful character and your body is all slack, and casual, then you are sending out mixed messages. If you are trying to play someone who is adult and dealing with a serious situation and at the end of every line your voice goes up. Then that message is that of a little girl.
Here is where you need to be in control. Now understand I am not trying to change you, just your acting. Your awareness of what the camera/ auditioners are seeing is very important. If you have not trained enough or worked enough with someone who can spot these traits, you need to. Otherwise you are mostly sending mixed messages. What that does is it reduces your chances for success. So get into class and knock off those bad habits.