When I first started here at Sydney, I thought I knew everything. But the first time I wrote an essay, I got a conceded pass. That means I just scraped through! I was used to getting pretty good marks in high school, so it really knocked me for six!!! I soon discovered that university lecturers have different expectations to high school teachers, and the work I was producing at high school wouldn't cut it here! So I enrolled myself in a free program run by the Learning Centre, on how to write essays. It really did help, and it was only a few hours.
The Learning Centre has a fantastic website with PDF downloads on all kinds of helpful things - everything from how to get the most out of lectures, to how to analyse an assignment, to faculty-specific advice.
I know it might seem like the last thing you want to do, but these downloads will really help you, I promise! The website is http://www.usyd.edu.au/stuserv/academic_support/learning_centre/resour.shtml
Good luck guys!