What I found, that helped heaps was if ever I was questioning something I was doing, I'd sort of think it out as me giving advice to someone else and it helped me to re-affirm what type of study I was doing at that moment was logically the most effective. Definitely go out to a few 18ths, you can miss less important ones if you have sacs that week, but for your closer friends definitely go because you probably won't be that productive if you're stuck studying on a saturday night thinking about what fun you could have had. Year 12 is definitely a crazy year, but (unfortunately) exercise is definitely on the agenda

it really helped release some stress and just be focussed. I am slightly hypocritical because I did push myself this year past what I should've to the point of absolute burn out; my remedy? Sleep and lots of it, plus a good movie out with friends. I am an insane hard worker so I guess I did push myself a little too hard, but for me I knew I could handle it. As long as you keep a positive determined mindset and take things seriously enough to put in a decent amount of effort and pride then I think you've done your best.
Make sure you organise to go out with your friends every friday night at the end of each term!! This was a fantastic way to relax and refresh after a stressful term

Term 1 is like Hawaii so you need to get serious about studying from day 1 and most importantly be really consistent so that you don't majorly STRESS OUT, I was already working hard from the start of the year so I didn't have to raise the intensity that much to keep my grades fabulous in term 3 which is the most stressful SAC minefield ever
Enjoy the Year 12 events as they come like the carnivals and formal ect.. and take it as something to look forward to whilst you work hard, there's nothing worse than regretting not working to your capacity and feeling majorly stressed about all this work you have. Set yourself almost a timetable each day to ensure all your tasks get done on time, and to be honest? I didn't block facebook in Year 12 and I DONT regret this! It really helped to destress and gain a feeling of I guess socialising with others that aren't in Year 12, or those that are from different schools. You gotta form really good social bonds with your closest peers and help each other throughout the year for support

Although be wary that some people may find ways to attempt to manipulate you for their own study benefits, so my advice is keep away from study groups IF it's only going to benefit them, you have better things to do with your time

ANNND my final point is about Jan/Feb I had an ATAR aim on the wall, then I took it down because it stressed me out!! What I would've done in Year 12, and regret although I did this in about April was to have the 1 aim of trying to get 100% on everything I do. It's all about taking it one day at a time, sure speculate on your ATAR... that's awfully smart to stress over that rather than on the SACs that count *sarcasm* what I mean is just (so cliche..) do your best and everything you get your hands on, and hope for the best too

I realised this when I was focussing so much on specific study score aims that once I got an A on a SAC and thought the world was going to end. My advice to you is to just aim for 100% everytime and know there's nothing you could've done better because you have to focus on each little bit of the journey and of course the support of teachers and friends.