A lot of people participating in the Flash Jam might be having trouble returning to AS2 from AS3, given the relative lack of documentation (and forgetting a lot of the AS1/2 pitfalls over time). As such, I think it'd be useful to list any tips and tricks you might've thought of while programming in AS2.
AS1 is also accepted because I imagine not too many people would've programmed in "proper" AS2, and instead resort to a hodgepodge of code on movieclips and timelines alike.
The AS2 Language Reference is available here. It's got examples of each function listed therein, which is a good place to start if you're having trouble recollecting what a function's supposed to do.