Please give us a short notice when you have earned the black belt of regex.
Such knowledge would be very welcomed here.
I tried to get into regex last year and got nearly insane. It starts simple but if you try to get the cases on the edge it becomes really crazy. A short hint: I found it difficult to adjust the regex expressions in PVD as you could not immediately recognize the outcome. Therefore I use a software called Flexible renamer (
http://hp.vector.co.jp/authors/VA014830/english/FlexRena/). When entering regex expressions the result is directly shown in a preview.