PHP autoloading is a topic that, once you’ve begun to employ it in your projects, is hard to avoid doing so in any project moving forward.
The challenge with learning how to do it, though, is learning aspects of object-oriented programming and what facilities the PHP standard library has to offer. On top of that, there are other advanced tools like Composer that make it possible, as well.
You have to walk before you can run, as they say, so in a recent series on Tuts+, I walk through how to perform PHP autoloading using object-oriented programming in the context of WordPress.

