Firstly, thanks to Hong Kiat, he recommend me this tip. Let me share a bit about QuickLook plugins for your finder extensibility. I believe most of us have already known that there are many useful QuickLook plugins out there. And according to me, these three QuickLook plugins are used the most :

Folder List

With this plugin, you can see what's inside a folder, reveal hidden items and even the exact time of the items' creation and modification can be shown.

BetterZip

Without unzipping, you can see all items inside your zip files. It's just like having another handy Finder inside your QuickLook.

Suspicious Package

This plugin will be useful for you, especially if you're usually paranoid. Before unpacking package files, you will be able to peek inside the package by QuickLook with this plugin installed.

Installing QuickLook Plugin

To install QuickLook plugin:

1. Launch Finder
2. Open Quick Jump with G
3. Key-in Address /Library/QuickLook
4. Drop *.qlgenerator Bundle Inside
5. Done