Hey
I'm currently at Yale (and got lucky with Harvard and Princeton admissions), so I might be able to help a bit. Make sure that you keep track of the time during the essay - it goes by surprisingly quickly. Don't erase anything on your essay, as it'll probably be really blurry when it's scanned in - cross things out.
Try sites like freerice.com if you need vocab practice, but for the CR section, underline or annotate the articles quickly as you go. The math section is ridiculously easy, so try and eradicate your careless mistakes. We don't really work on grammar in Australia, but you'll get used to it whilst doing any practice SATs.