Past papers, do as many as possible!
You can find a lot of trials on this site, and just go through as many as possible.
If you feel you can't do it because you don't know enough, do it open book (with your notes or textbook or the answers), and then do it again closed book, and mark the answers
Getting as much exposure to the questions as possible is essential, because they recycle a lot of questions with a few different things such as the wording and numbers (there's only so many things they can ask before they change the syllabus)
Learn the HSC verbs and how to answer each other them (that are relevant to chem and physics)
http://www.phys.unsw.edu.au/~jw/glossary.html
Notes and palm cards are good, as they're portable however you should solely rely on these - read them on public transport or before you go to sleep or something