I actually had a discussion with my boyfriend on this. He picked "low scaling" subjects such as Biology, but he excels at it. And I picked "high scaling" subjects such as 3U Maths, 3U English, Physics and Economics with a "low scaling" Business Studies.
And we have come to this conclusion:
1. Throw out the concepts of scaling first (do not even think about it yet)
2. Identify what subjects you enjoy, and what you feel confident and strong in (based on Year 10)
3. Now bring back scaling in. With your subjects, all of your subjects are "high scaling" except Legal Studies
Now be realistic. How well do you think will you do in Year 11? Do you think you can manage all subjects and get high marks and rankings?
Because the jump from Year 10 to Year 11 is very different. Especially the difference in English Advanced and English Extension 1. Additionally, will you cope? Because the jump from Year 11 to Year 12 is even more intense than Year 10 to Year 11.
Now you might look at my Step #1 and be like "Wow, what dumbass would forget the concept of scaling?". Me. Even though I have "high scaling" subjects, I still want to achieve the highest marks and avoid complacency by believing that my "high scaling" subjects will improve my shitty marks if I get lazy in Year 12 because I believe scaling will bring me places.
Whilst having a long-term scope is good, you are in Year 10 and the first step you need to look at is your own personal strengths in subjects, reflective in Year 9/10. I personally do not think you need to look into scaling until way after.
TLDR; PICK THE SUBJECTS YOU HAVE AN INTEREST IN AND YOU KNOW YOU HAVE STRENGTHS IN. NO POINT HAVING SHIT MARKS AND SHIT RANKINGS WITH A HIGH SCALING SUBJECT.