In Thailand, women should never touch a monk. When handing someone something, like money to a cashier or anything else, you should use your right hand. It’s impolite to use your left hand (and the left hand is used for wiping your behind).
In Thailand, do not eat and walk at the same time.
In China, people do not go Dutch. You should offer to pay, even argue or fight over the check, but if you want to give someone face, ultimately let them win and pay. In Thailand, the older, more senior person should always pay.
In China, when drinking, you should always drink with the other people at the table and touch your glasses together in a toast. It’s not to each his/drink at your own pace. Everyone drinks together, i.e. takes sips or does a “gan bei” (bottoms up) together. When touching glasses, the younger/inferior person’s should be lower than the older/superior person.
In China, when eating family style, don’t take the last piece of a dish, e.g. don’t take the last dumpling from the plate. Always leave the last piece.
In China, 4 is an unlucky number and 8 (and 6) are lucky numbers. Applies to multiples as well. So, for example, if you were giving a tip or red envelop gift, you wouldn’t give 40 or 400, you would give 80 or 800.
If you do a web search, you will find more, e.g.:
Ten Taboos in Thailand
• Never touch a person’s head. …
• Don’t point the soles of your feet at another person. …
• Never step on money when you drop it by accident. …
• Don’t move or pick up objects with your feet. …
• Criticizing the royal family. …
• Dressing inappropriately when visiting a temple. …
• Touching holy relics. …
• Touching a monk.
Basically, remember that, in Thailand, there is a “hierarchy” to the body. The head is the reverential and the feet are the lowest/dirtiest. The left hand is dirty.
Good Resources: Lonely Planet’s Cultural Shock and Cultural Smart Books