Yii's by-default directory organization works well enough, but there are several steps one can take that improve the security and serviceability of the system, especially in the context of multiple Yii projects on the same machine (including multiple versions of the same project).
In this short how-to I will show how to customize setFlash() to display messages (flashes) styled to be success confirmation, error report or notice information. And how to achieve displaying errors in other way.
I have seen a couple of articles about how to integrate external libraries to debug our PHP code (i.e. firePHP) but after you read this article you will realize that there is no need for such libraries when using Yii.