So what brings a beginner up to the next level? Well you have the core, better regexs, references, module use and creation, and OO modules.
The one thing that I don't see listed but think is important is list processing. The appropriate use of map and grep can make programs shorter and much more readable. I think it's a core skill that is often overlooked.
I definitely recommend module use be stressed before you move on to module creation. But when you do move on I find it useful, depending on the audience, to mix OO with the modules and packages discussions. The implementation of OO Perl makes it ideal for clarifying, questions on modules and packages. It also allows you to put off dealing Exporter( and it's difficulties), while still getting working, idiomatic perl modules written.