If you are invited to a Thai's house:
• Arrive close to the appointed time, although being a few minutes late will not cause offence.
• Check to see if the host is wearing shoes. If not, remove yours before entering the house.
• Ask another guest to confirm the dress code.
• Step over the threshold rather than on it. This is an old custom that may be dying out with younger Thais, but erring on the side of conservatism is always a good idea.