Of course, for much good guff there is my book “Aerobatics Down Under” – the Kindle version is only US$3 or about A$4 at https://www.amazon.com.au/dp/B07PXY467M
A good place to start is with the definition of aerobatics discussed at http://aerobaticsaustralia.net/?p=27
Many of my articles and other documents are about aerobatics so this page will have stuff that you generally won’t find anywhere else.
This draft AC 91.15 was developed with the assistance of a number of us in industry and still had some technical issues at this point. With that small group of so-called subject matter experts from industry I was dismayed by the lack of understanding by one or two of some important stuff in this AC. Seven years later it had been developed into CAAP 155-1 which became obsolete over five years ago as there were significant and widespread changes with Part 61. Apart from those dangerous issues with it. I’ve heard that CASA is now working on the AC for aerobatics. I can hardly wait – twenty (20) years after the final draft below!
Finally, into competition aerobatics and changing the techniques to earn higher scores per this guide: