Always remove your shoes, socks and hat and wear conservative dress prior to entering a temple or home in Thailand. Also be aware that it is considered rude to show the bottom of your feet toward your host, which can most easily be accomplished by sitting cross-legged. 

Never point at a person, or touch their heads. In general the people of Thailand are not used to being touched by strangers, so tapping, hugging or putting your arm around someone is likely to regarded as a violation and cause unintended offence.  

The standard greeting amongst Thais is not shake hands but instead to use the Wai, raising the hands, palms and fingers placed together in a manner similar to prayer, touching your body between your chest and head, accompanied by a very slight bow. 

If you need to attract attention, motion with the palm of your hand. It is a common gesture in many societies to affectionately ruffle the hair of children, but the head is considered sacred in Thai society and such gestures will not have the intended effect. 

Avoid political comment and criticism, and especially do not make comment regarding the Royal family, which is a criminal offence. 

Visitors to Thailand should be aware that it is highly likely that they will witness attitudes towards animals which may distress, and prepare themselves in advance to deal with these matters with calm and sometimes considerable restraint. 

Overt public displays of affection between couples is frowned upon, particularly in traditional areas, and shows disrespect to the native culture.  

Tipping for services in Thailand is in general unnecessary but will be accepted by Taxi drivers, tour guides, restaurant and hotel staff.   

When dining, the fork is used for prodding and manipulating food on the plate but eating should be performed with the spoon. Sticky rice is often eaten with the hand, particularly in the north, for which the right hand only be used. Despite the instinct, you should never lick your fingers afterwards. 

It is not the practise in Thailand, especially for women, to touch a monk, or even their robes.