Hi there! I sat the exam in 2024. One of the biggest tips I could give anyone doing any kind of selective entry test is to not over complicate it, only stick to the curriculum. Nothing extra, nothing less. The Oxward year 9 and a bit of the year 10 textbooks (mainly for advanced algebra) really helped me for math's. As for the science components, make sure you are able to analyze data and interpret it correctly. Also make sure you know how to write a lab report. Try asking Chatgpt for prompts for informative reports and continuously do them. For NR, I mainly recommend doing Henderson's tests. They are not a replica of the actual test, but most aspects were accurate.
Aim for 2 superiors or more (to standout from the crowd) but don't worry if you only got one, because a bunch of people I know got in with one superior.
Lastly, please don't overwork yourself. If you done the sehs test for year 9 entry, The maths and NR tests are quite similar. Maybe just a little more harder. Personally, what I done was alternately study maths or science everyday of the week for a hour and then spend another hour on school homework. This is more than enough.
I hope this helps!!