* In general, I think solving by inverse obscurity is the proper way to successfully complete the puzzle, so I always aim for the order: purple, blue, green, and yellow.
* Had to recall a line from Pirates of the Caribbean, which used the archaic term for things you own (ie - effects) to help finalize purple.
* Initially thought "green" or "sound" would work for blue.
* Green was pretty easy; I thought it should be yellow.