just try to stay within the "smart" section of the class in terms of rankings, get the EAS/interview/whatever helps gets you into desired course (err....but try not to abuse the system), study your ass off 2 weeks before the trials, relax, study hard again 1.5 months before the hsc, relax, get bored, relax somemore, freak out over your results, get your results:
from this point on you either get into your course, get into a different but equally desired course, get into a less desired course /uni and transfer next year, get into the DFEE for your desired course, go to TAFE or get a job and earn a good +$100k with some bonus experience before anyone else even finishes their degree.
the HSC is overrated as long as youre not aiming for one of the +95 cutoff courses then you shouldnt be stressing too much. remember, the UAI cutoffs are all about demand, theres no point stressing over over-achievers who are aiming for medicine and pharmacy when you just want to study at a campus 5 minutes walk from your place doing a course with a cutoff of 70. most of my friends didnt quite make it to where they wanted to go and just ended up at UWS, spending another few minutes travelling to a less prestigous uni. another was quite disappointed with his results (he did put in a fair amount of effort) and decided to just enter the workforce instead.
barely worth killing yourself over.