One thing to do is try reading seekers of perl wisdom, and solving other people's problems.

That's an excellent answer. I'd also offer that few professors in undergrad classes test for things they didn't cover in class. You should go back through all your notes and do the work therein again. And if you don't have enough confidence in your own notes, ask a classmate to meet you at the copy shop and swap notes so you have another set from which to work.