How to be a good performer

As well as media, I have taken Drama as an A level. I am very keen on making my performance as believable and as realistic as possible. Therefore I done some research into how to be a good performer. I found the following things:

1. Be free. Try and be as natural as possible, therefore keep your limbs free.. DON'T BECOME ROBOTIC
2. Display a range of emotions in your face
3. Become the character
4. Believe in your abilities to perform