When visiting or living in another country, especially one with a culture as different as Thailand, it's worth learning a little about the culture and customs.
Not only will you go home with a little more knowledge of the world around you but it will certainly help when meeting the local Thai people. Much like the rest of Asia, Thailand is a predominantly Buddhist culture and much of its rules about how to be polite come direct from their religious beliefs. Though many of the customs may seem strange to a Westerner it's always worth remembering that you are in a foreign country and are ambassadors from your own, so though you may not get it right every time, an effort to understand and use Thai culture and customs will certainly be appreciated in Thailand.

Hands and Feet In Thai culture the head is spiritually the highest part of the body ans the feet the lowest and considered unclean. You should never touch any adult Thai on the head, especially if they are older than you, and it is even wise to avoid the heads of young boys as one day they may become monks.
You should never point your feet at someone or an object as this is considered disrespectful. A child can burst into tears because he has done something wrong and instead of his Father hitting him or scolding him he simply pointed his foot as the boy to show he had no respect for him.

Greetings-How & When to Wai The traditional Thai greeting is the Wai. The Wai is a prayer like gesture made with the palms of your hands begin put together accompanied by a slight nod and sometimes a lowering of the eyes.
The height of the hands varies as to the status person you are waiing, but generally speaking if it is person of importance for example, a monk or an older person, then the top of your fingers should be raised to the top of your nose.
A lot of people make the mistake of waiing too often and waiing a person they need not wai. The Thais will look on this as a bit strange. You do not need to Wai shopkeepers, waitresses or people in the service industry though they may Wai you, and as a general rule a foreigner needs to Wai very few people and they are either people older and respected personally, a friend's parents, or the owners of a home you are visiting.You will also find a handshake works just as well especially with a lot of Thai people, as they know this is the foreign greeting and is still a respectful thing to do.

Losing Face A lot is said about the tradition of a Thai losing face. There is no point explaining it here as foreigners have the same tradition. To understand it better and to put it in very simple terms, you just need to rename it is Western terms. Losing face is when you are made to look foolish in public. Of course the concept to Thai"face" can be explained in much deeper depth that this, but the above is a simple rule that works well for everyone.
To make some lose face is unadvised as people often take an unkindly to this as you would in the West. Be aware that for a Thai to lose fase is a very bad thing so try to avoid making them lose face at all costs.

howing Affection The Thais especially elder frown upon public displays of affection, even innocently holding hands and certainly kissing in public. This is becoming less now as Thailand becomes increasingly modern and westernised and many of the younger Thais will not be bothered by this.

Dress Shoes should be removed when entering a Thai home. You'll often see stacks of shoes outside an apartment room.
If you visit an official place such as the immigration office, always dress neatly. Shirtless, with no shoes on will not start you off the right way with the officials as they consider it disrespectful.
When going to a religious site again always dress respectfully and without showing too much flesh. Hot pants, shorts, no top etc. are not fitting clothers for these places and you will often not be allowed into them.
Shoes can be worn inside the temple grounds but not in the area where the main Buddha image is kept.