He he,
Lesson #1 - Never take Ianto for granted
Lesson #2 - Always listen to what Ianto says, even if you think it's boring
Lesson #3 - Always do your homework about were-rabbits before re-engaging in sexual proclivities
Lesson #4 - If it looks like a rabbit and quacks like a rabbit, it may very well be just a rabbit.

I could probably think of more, but to be honest my brain's a bit knackered after Challenge week and Amnesty week rolled into one!