In this lesson I wrote that you should try to write 'perfect' essays when you are practising at home.
What I meant was that you should take as much time as you need, check everything carefully, use a dictionary or the Internet to find better vocabulary, and generally do your best to write an essay that you probably wouldn't be able to write in an exam. You should be able to score at least one band higher when you're practising like this, compared to the score you get in exam conditions.
Ask yourself: Am I pushing myself to write essays to the best of my ability when I'm practising at home? Or am I simply testing myself or staying in my comfort zone?