What do you think someone about to learn Perl should know and/or keep in mind ahead of this awesome journey?

Phrasing it this way implies two things: 1) that there's some unique prerequisite for learning Perl. 2) That learning Perl is an awesome journey.

I do not agree on the first part. I don't think there's anything you must have to learn Perl. You don't even have to like Perl. I know people who hate Perl with a passion (and can actually motivate their reasons quite well), but who can still program pretty well in Perl.

As for 2), I think that isn't true for the vast majority of the people who know Perl. For most people programming in Perl, Perl is just another language. Most of them have learned it as part of some job. The average Perl programmer actually has a life outside of his job. In his free time, he takes his dog for a walk, goes with his kids to the playground, and takes his wife out to dinner, instead of writing CPAN modules, hanging out on Perlmonks, or finding himself superior to PHP or Java programmers. The overwhelming majority of Perl programmers is as fond of Perl as most carpenters are of their hammers. Carpenters don't consider their first year of playing with hammers "awesome journeys" either.