Ensure that when you synthesise a definition for a particular term, that you have integrated appropriate terminology that demonstrates your thorough understanding of the topic. I found it very effective to re-write notes as opposed to just reading over them. So, instead of reading a paragraph about topic A, read over it once and then begin to write out the notes once looking at your notes, and eventually you'll come to a stage where you have embedded into your mind the topic.
In regards to note taking - personally, I'd take down a lot of notes when my teacher was talking about an upcoming SAC that we had. I'd write down everything my teacher hinted out about the SAC, to maximise my SAC score & ranking. My notes were short, succint and to the point. They would encompass both things I already knew + handy little notes to further broaden my understanding. If you don't kniw whether something is important, refer to the Key Points section of the VCE study design. Adhere to the study design, and you wont go wrong.
Best of luck

Yacoubb