How to NOT be singled out as an American (as much)
1. Don't Complain: The biggest American peeve I've heard people talk about so far is that we bitch and moan too much.
2. Take it easy: Don't stride like you've got some place to be, even if you do. You'll get there when you get there, and even if you're late you'll still probably beat all the Irish folk there.
3. Don't lean: Seriously, I have yet to see anyone leaning against anything... and while you're standing there, not leaning your feet best not be more than 5 or 6 inches apart. No comfy spread leg leaning over here.
4. Don't constantly compare things to the US: You're not in the US, YES things are going to be different. Just enjoy the changes and don't always think/say "oh in America this or that is better"... you'll just piss me and everyone else off.
5. Don't drink the Guinness: One night I ordered one and all I said was "Guinness" and the bartender said "oh, you're an American are you?"