i'm in a similar position as you, i have friends who are buying all these guides etc. and i really don't want to waste money on useless material
i'm not going to bother buying anything for methods except the textbook, like the fellow VNers(?) have said, methods is about practise, so i think that just doing all the textbook questions
properly will be enough as well as all the practise exams the school gives you.
i find physics a bit harder in terms of understanding the concepts, so i'm purchasing a set of Jacks notes to understand the concepts, however, other people can pick up concepts much faster than i can and they don't really need an 'aid' in understanding concepts. but purchasing material for physics should probably just be on understanding concepts, once you understand it, it's just like methods and you have to keep practising and applying your knowledge. i don't want to rely too heavily on my cheat sheet, which was a mistake i made in units 1&2 this year.
for english i borrowed some study guides from the library (i'm not gonna bother buying them, i think they are a waste of money, personal opinion). after skimming thorugh a few, i got some basic ideas and then from there i started building my own ideas etc. and have put them into a reading log (part of our holiday hw)
we have to buy checkpoints for every subject at our school, so i've just bought older versions of everything to save money, i don't know how useful they are going to be but hopefully i'll get some use out of them. if you really want to get your hands on study guides, notes etc. i suggest borrowing them from the libarary and making a note of anything really important (even if your friends bag you for going to the library, just go anyway

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this is just my view, and it is quite similar to the people that have written above me, but everybody's different and some people require more resources than other people. and i asked a friend about lecturers who did vce this year (she's your average student 87.02) and she said lectures are the biggest waste of time and money -> but i'm not exactly sure how right she is because i've never been to a lecture...