Post-qualification I joined a flying club with a nice new(ish) Skyhawk complete with autopilot. I didn't pay much attention to the AP when I had my club checkout, thinking I would rather hand fly. Like many autopilots this one is activated by a thumb button on the yoke where you might otherwise expect the mic key to be. I discovered the hard way one day after take off when I had to fight to stop the plane turning in the opposite direction I wanted it to. Fortunately I worked out what was going on before I killed myself, and I now know how to operate the AP (it's a great tool for lazy cruising btw).