Basically, Adobe Livedocs, and trial and error. Although from a rendering perspective just knowing the theory behind it (write code to just rotate an image without concern for quality and it's instantly clear that it'll always be slow) gives you pretty much everything you need to know - it's just connect the dots from there.
Also, Flex Builder is a bit of a dud, but its profiler is very good. If you can afford it, it will give you very good insight into your code bottlenecks, if the $$ is worth it just for that. I use FlashDevelop to edit in still.
P.S. Sorry if I'm hating on Flash a bit too much throughout my posts. There were a few trivial bugs with serious implications that directly delayed our release, so I'm still quite annoyed. I'm back into Flash for the next project, though, because customers are more important than development comfort!
Thanks for the great information. One quick question... when you say you're "back to Flash" for your next project, are you talking about moving back to Flash (as opposed to Flex) as your dev tool/programming paradigm or did you stray from the Flash engine entirely?
Oops, I should have said Flex. I meant it in the 'oh well, back to the grind' sense. :)
All of our titles have been Flex so far and it will stay that way for a long time yet, I imagine. We started Stunt Pilot in the Flash IDE but it quickly became apparent that it was a really ineffective development environment for what we were doing. Flex has its problems, but at least the core model is more appropriate (i.e. entirely source code, command line compiler).
Also, Flex Builder is a bit of a dud, but its profiler is very good. If you can afford it, it will give you very good insight into your code bottlenecks, if the $$ is worth it just for that. I use FlashDevelop to edit in still.
P.S. Sorry if I'm hating on Flash a bit too much throughout my posts. There were a few trivial bugs with serious implications that directly delayed our release, so I'm still quite annoyed. I'm back into Flash for the next project, though, because customers are more important than development comfort!