I came first, but I go to a average school (15 or so in the class).
I think the key to coming first AT THIS STAGE is to really open your mind up to maths. Like do some reading on the history of maths. Find out the different views and approaches to maths (like the greeks and their geometry). Just get a really broad overview of the different areas of math and how it all came about. Of course don't just read it all, try proving/making up problems of your own based on this knowledge. E.g When I heard about archimides's method of approximating pi using polygons inscribed in a circle, I went out and tried to do it myself. Ended up finding an expression for pi in terms of a limit to infinity. And just to my luck a similar question came up in a trial exam involving proving the volume of a cylinder was equal to some limit. Because in extension 2 they like to test you on unfamiliar things. Everyone can find the modulus of 1+i but not everyone can do probability because its all intuition, no real formulas involved. Thats what you should do right now, but once you get into the heat of 4 unit, I suggest you focus more on the content. I take it you want to do math (or math related) courses at uni, otherwise why would you want to come first, so yeah I found just getting a really general scope of the real idea of math (beyond school) really helped me to come first. And finding this stuff isnt hard if you know where to look. As a teenager, youtube actually has some fantastic math channels (numberphile, njwildberger), which makes math fun! For tutoring, I did get tutored, but my tutor was actually only at a MX1 level, so I spent the time teaching 4 unit to her, which apperently is a very good method of study. But there's probably a lot of smarter 4 unit people on this site than me, so probably wait to see what they have to say.
