The other thing I try and do is try and keep the main SWF below 200KB (code and vectors only) and load in all Bitmaps, Sounds, etc. at runtime – either with a preloader/asset loader, or my own ImageHolder cache which dynamically loads and caches images.

For sound, its a bit more complicated – if you just load mp3 on the fly you end up with a delay for the first play. Instead, I embed sound and music in a separate project / SWF with class/linkage IDs, and then create sound files using a factory function in the loaded SWF. That way I can preload all the sounds and create them instantly without worrying about subsequent load delays.

You can do the same with “image packs”, which is useful when you want to separate your game/program code from UI elements, and hand those files off to a flash designer/traditional designer to work on separately from the main project.