Yes, I did know that these things were true before I re-learned them.

• Transistors work best when correctly oriented in the circuit. (I checked the datasheet, I checked the orientation with a diode checker... and still I got the collector and emitter in backwards. Twice... and yes, I did check the datasheet pinout in between!)
• Molten solder is uncomfortably hot. (This I learned at a tender young age, before my immortality wore off. I now try to avoid soldering while wearing spandex bicycle shorts. I also try to avoid placing myself between the potential drips of molten solder and "down".)
• The shiny, metal-colored end of the soldering tool is also uncomfortably hot. Grab the plastic end (the one with the cord) instead. (I don't feel bad re-learning this. It seems that many people have had to re-learn this. I am happy to report that my reflexes are improving dramatically, and I now recognize that I'm grabbing the "wrong" end, and let go in a timely fashion.)
• Don't probe live high voltage circuits. (OK, I'll admit: 120 VAC isn't terribly high voltage (it just tickles, with no sting), and that's about the highest voltage I've been "dumb" on so far. However, this is a lesson well learned.)