The head is the most sacred part of the body, so should not be touched. The feet are the least sacred, so when sitting they should not point at anyone - most Thais sit on the floor with their feet tucked under their bodies behind them. To point, particularly with foot, is extremely insulting.
The feet in Thailand are considered spiritually as well as physically the lowest part of the body. Donít step over peopleís legs, even in a crowded place such as on a train; wait politely for them to move out of the way. Do not point things out or pick things up with your feet. And do not wave your feet around people's heads! If you accidentally touch someone with your foot, apologise.