I'm in Year 7 so the way I write notes may be different to yours.
I study around 4-6 hours during the weekends, and 2-3 hours during the weekdays (excl. homework) which is a rough idea of how much you need to study if you wish to do well in the future, instead of just concentrating in year 11. A lot of people get into Year 12 and still don't know the basics.
I would start by getting a 4 subject notebook from officeworks, Colourhide is a pretty good brand. Get the ones which divide the book into 4 parts, so you can use it for 4 subjects.
To study for maths, write up formulas, and examples of how that formula is used in the context. Also write any terms you need to know, etc. For English, you will need to write notes on the themes, characters, setting, and whatever you may be studying at school. Use bullet form. For example, if you are studying Julius Caesar, write a statement about each character and use evidence, I find quotations to be the most useful. For science, writing down notes on the outcomes is fine, and answering key questions (main topics of that topic). You don't really need to write notes for languages, studying it from the book is fine.
Once you have written all your notes, keep studying them at a regular basis. It will soon become knowledge and you will be able to use that information for your examinations. Make sure your notes are accurate, or else you will be wasting your time.
Best of luck.