You should have a look at the marking criteria.
To get 1/3 for instance, you only need to attempt to describe the text.
To get 2/3, you need to find some techniques and provide some sort of adequate explanation.
To get 3/3, you need to have aptly chosen techniques and a well-written response.
I've spoken to various HSC markers, and I remember a couple of them saying that it's okay if e.g. one of your techniques/explanation is shoddy. They'll just look over it and see if the rest of your response is good enough. For instance, if it's a 3 mark question, and you've written on 4 techniques with good explanations for 3 of them, but your last one is a bit dodgy, you can still get 3/3.