Do:
-be creative.
-look at other art (web/print/3d/motion)
-use Flash if it enhances the experience! best if you want need a site with music and sound
-learn the extents and limitations of your programs, and when/how to cross over between them

Don't:
-let the technicals get in the way: learn the system(s), then if they are good, your creativity shouldn't be limited and at the same time you know what is possible.
-get locked into one style (see Do #1 and 2)

=my views!

great thread!
-CC