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.
- ...