In maths, you don't need notes - just work through the textbook doing the exercises.
English, read your texts (again hopefully), start a quote bank and start pulling apart your themes, characters, techniques, author's values, ideas etc. Generating your own ideas rather than just coughing up other people's is what's going to make you stand out.
Theory based subjects, definitely don't just read someone else's. Your goal is to understand and remember the content, and that's not going to happen through reading without processing - it'll just be in one eye out the other.
Instead, when you're reading the textbook and/or someone else's notes:
- verbally summarise in your own words after reading each paragraph
- take really concise summary notes, again in your own words and probably with a different structure, just so you're processing it and understanding it
- google anything you don't get (and try Khan Academy/youtube vids too - combine multiple sources in your notes)
- test yourself afterwards by creating questions from the content, like 'what is recession and what is its impact', and trying to explain it without notes rather than just rote learn
Make sure that every time you read, you've really understood and process it, and verify this by testing/active recall. It takes more effort, but it's far more efficient to actually learn it thoroughly in one go so you don't have to spend very long.
Edit: contrary to above, I wouldn't try prac exams yet - leave them till you've actually learnt the content, because otherwise they're not that helpful.