In addition to Zaxo's suggestions, take a look at perltrap and search the Monastery for additional discussions about gotchas. (I don't mean to give the impression that style should be informed only by gotchas; but some of them can systematically be avoided by a good style guide.)

Then read Abigail's Coding Guidelines for Perl. With any style guide there will be things you disagree with; Abigail's is notable in that everything comes with a rationale you can learn from / argue against.