Apple doesn’t make it terribly easy to customize certain aspects of Mac OS X. That’s completely understandable. Mac OS X is set up to be simple and elegant from the start, and countless people tinkering with this would likely lead to problems. Despite this, there are plenty of changes to Mac OS X and its applications you can make, if you know where to make them.

Tools like Visage and TinkerTool can give you an easy to use interface to change a good deal of Mac OS X’s “hidden” settings, but don’t cover everything. If you just want to jump in, or don’t want to be nagged by shareware notices, you can grab any decent plain text editor and make changes yourself instead.

User-specific preferences are stored in /Users/username/Library/Preferences, where username is your user name. The files end in .plist and are prefixed with com.apple for Apple’s applications (including Mail and the Finder). Opening up and editing these files can let you change a wide variety of things, but can be a bit dangerous. Be careful before you change anything and be sure to keep backup copies!

As an example to get you started, you can find Finder preferences in com.apple.finder.plist. A boolean option will be defined by a key tag containing the option name, followed by true or false tags. The following sets the option AppleShowAllFiles to true. This makes the Finder display all files, including hidden ones you probably don’t want to see anyway.

<key>AppleShowAllFiles</key>
<true/>

A restart of the Finder (log out and log back in) will cause the new preferences to be loaded.