Keep your own modules in dedicated subtrees of your project. For example, create a subdirectory lib as the root of the subtree containing all *.pm files. Note that you can have more than one such subtree. For example, you could also create test/lib to store modules that are only imported by test scripts.

Add the root directories of your subtrees to the @INC path (see the section called “Perl Include Path”). For example, add the entries lib and test/lib there.

Map package names to paths in the subtree (and vice versa). For example, store code for the package Foo::Bar in file lib/Foo/Bar.pm and ensure that lib/Foo/Baz.pm contains only package Foo::Baz.

Store your Perl scripts anywhere you like in the project. For example, in subdirectory bin or cgi-bin.

To import from a package, use it, rather than require it. For example, use Foo::Bar; rather than require '../lib/Foo/Bar.pm';