There's absolutely no need to take down too many notes- get a copy of the syllabus and just structure them in terms of the dot points. Keep in mind that writing pages and pages of notes will not help you in the HSC or half-yearlies or whatever, you're much better of writing practise essays and sticking to 1000-1200 word limits.
There really isn't much you can write in 40/50 minutes so you don't need to know every tiny little detail, and knowing all these little details will probably make you more inclined to write 'descriptive' rather than 'analytical' essays.
Writing essays helps you organise things in your mind, and you'll probably do better by 'twisting' the information you know to fit the essay question in the exam than by knowing a truckload of random facts but not being able to organise them into a decent essay.
Read and highlight ALL the info your teacher gives you and do all your homework for sure, DO find some good quotes for historiography, but don't go overboard with notes.