Point taken about the run up area, but here are a few more...
"line up and wait after the landing...", instead of "after the landing aircraft, line up and wait"
Not reading a chart and flying at FL 075 instead of below FL055, and avoiding contolled airspace!
Trying to be too quick and smart and gabbling the inital message a la how they perceive airline ops. Remember someone has to listen absorb and pick up the right coloured ATC strip.
Flying aeros close to a busy airfield without even a courtesy call.
Above is not exhaustive but I think the basic problem is lack of capacity. The winter is over and everyone is desperate to fly. Why not stick to a few circuits or the local area on that first day? I often hear a tremendous sigh of relief after landing and not having made too many cock ups. Is that the way we finish work in our daily lives? And what would happen if you had a real emergency? How often do you practice PFL's?