I did literally no prep at all, just winged it completely during the exam, and I got 79 so do with that information what you will
(although I've debated for eight or so years so arguing comes very naturally to me)
I did write a quick thing the other day about what i'm planning to do this year to (maybe?) increase my score which you can see here:
So I did the LAT last year and I'm doing it again this year - what they mean when it's 'in the moment' is that you literally have two questions that could be on any topic.
Last year one was analysing an argument - we were given an article and had to discuss the strengths and weaknesses of the author's argument.
The second question was constructing an argument - we were given a topic and a bunch of stats/sources and we had to craft an argument based on that.
Due to this broad nature of topic it's really hard to prep for it the way you would the HSC, and often you do well without prepping. Last year I went in completely blind and got a 79 (for context, the median score for UNSW entry last year was 74).
What I'm planning to do this year though is just look through some persuasive techniques, à la Year 9 NAPLAN, just to give my first section response some more structure and credibility. I'm not going to do much beyond that, though.
Good luck!