One really useful skill that I think has been lost to the internet is the ability to hold a good debate. I learned my debate skills from high school Chemisty (don't ask, idk) but I remember that to have a good argument, you need to research evidence for your case.
Evidence is also useful to avoid getting your Wiki page deleted, but that's a different story. XD

So what brings on this PSA? Well lets just say you won't find many good arguments on a political blog and leave it at that.
Though if you want to mess with a speaker, just hold up a sign like Digo's when they make a point that sounds more like opinion than fact.

Though from personal experience, expect to get thrown out afterwards. XD