Place all your codes in one place
This would rather be an old one for many but seeing many files that people send me to have a look into and help clear some problems, and the way they still code the old Flash 5.0 way, I would like to suggest this small tip for Flash MX. Always place your codes on the main timeline (_root) preferably on a single layer dedicated to Actionscript. Of course, it was not possible in the pre-Flash MX days, but now we can reference any object from the main timeline. Let us stop the bad habit of putting codes on the MCs or on buttons. Avoid the lust of putting codes on MCs and buttons, take a bit of more time to understand how to access and target objects from the main timeline. This will be a real blessings in due course of time. Happy Coding.