Most of these could apply to any list of cultural etiquette. but there are some rules I’ve certainly broken:
Never stick your chopsticks straight up into a dish.
Don’t use chopsticks for any non-noodle dish at a Thai restaurant.
Eat pho out of the spoon.
Receive all Korean dishes with two hands.
Eat nigiri in one bite and with your hands.
Personal rule: clap with both hands.