PBP probably has some tips, but other than that, I can't think of anything off the top of my head, neither a program nor a list. To start one...
".*" is greedy, which will probably do something you don't expect in the future, so think about how you're using it.
be careful with "^" and "$" when not doing line-oriented string processing. But don't sweat it -- most of the time you are, so they do the right thing.
be explicit when you might have to touch Unicode, e.g. "\d" matches all kinds of junk that the rest of Perl doesn't think is a digit. IMHO, all regexes should have the new "/aa" modifier on them, unless you know the reason they shouldn't.