MMHS hello! I don’t think my testing experience would be that similar to yours, as the test has shifted over to ACER. However, I’m still happy to give you my perspective!
For me, I found reading comprehension and numerical reasoning to be the easiest sections, although generally the difficulty wasn’t too bad across the board; it’s more so the time pressure that makes it difficult. I didn’t go to tutoring or anything for the selective exam, so I didn’t really have an expectation of how difficult the tests would be aside from comparison to the sample tests on the government website, in that the real test was definitely much harder than these. It was definitely still doable though. If you do tutoring (esp. at James Ann and Henderson), I’ve heard the real exams were of similar difficulty.
As for Verbal Reasoning, most of the vocabulary was pretty comfortable and familiar to me, so I wouldn’t say it was overly difficult (probably above your standard year 8-9 level though - as expected). Also, even if you don’t know what a word means, the process of elimination always works as a backup (which word doesn’t fit in, what do you know about the prefix/suffix/patterns within the word, etc.). I think the best thing to do to prepare is to expand your vocabulary naturally by reading some high level novels.
I honestly don’t remember much of what we were tested on in math, but the concepts weren’t overly difficult (just revise year 8, year 9, and year 10 concepts -> nothing over that was really on the test), probably most important to work on your algebra skills. Finding tricky questions in your math textbook (or a year 10 one) or from math olympiads is helpful. Again, the time limit was what really got me for math, but I think the best thing to do would just be practice questions and practice papers under timed conditions to get used to the real exam conditions. There are some free ones online on the government website (which from my experience, are pretty easy compared to the real thing), but there are other paid resources you could buy if you wanted to get more practice.
As for writing, I think it has changed quite a bit since I did it, but we were given a sheet of paper with images and text as our “prompt”, and we had to write a story on it (a full story). Many people, including myself, didn’t finish it though. Doing well in this section definitely helps you stand out, as it was the worst section for most.
If you have any specific questions please let me know, I’m happy to answer!