Before I was using my teeth, then one day I randomly tried using my hands. It surprisingly worked much better and I'm shocked more people don't do it this way.

Kidding =]. I actually don't have a better way of opening jars, it was more an example to show the triviality of the type of problems this kind of trial and error can work for. Maybe a better example is figuring out a repeatable way to get a stubborn door to shut. Things like that.

EDIT: Actually, you probably already know this, but if you turn a jar upside down and hit it on a counter top, it can knock the lid loose enough to twist off. I didn't mention it because I didn't figure that one out on my own, but if you're looking for jar-opening tips, that's a good one.