And how do you learn C?

Get enrolled in a class, or get a good book on the subject.

People giving instructions on compiling a perl module are doing just that; giving instructions on compiling a perl module, they're not givin a lesson on C. So the instructions you will find would be specific to that module, and will not usually help you compiling, for example, Mozilla.

Unfortunately, many of the "best" instructions I've seen for programming related stuff are awful

That's cause you're looking at the problem from the wrong direction. If I publish a module that has an XS extension that relies on the 'foobar' library, I'm not gonna explain in the documentation how the operating system loads libraries, and how the compiler links the code, etc... that would be a different type of problem. All that you're likely to get in the docs would be information about how the module works with 'foobar' and specific issues you need to note, and that's all.

Again: want to compile effectivly? learn C. Otherwise, look for binaries, or get someone to compile them for you.