Before my first match ever in Europe last year (Puget), my team captain gave me a break down of the things refs would catch people on. Hand on head, talking at all, arguing, etc.
I was amazed! I was so used to mouthing off constantly on the field, and to be told I couldn't was a bit of a shock. However, I paid attention, and it really wasn't that hard to remember.
The best thing I can say about European refs, is that while they do enforce rules very strictly, they do so in a consistent manner. Was I pulled on some weird 1:1's? Yep, but so were other teams. I'll take consistent calls all day long every day.