What do local Thais see when they see you, a foreign tourist? -  Knowing this will give you a good starting point for understanding the common ways of dealing with people you meet.

Thais see other people as humans that all fit into one of three 'circles'. The closer the circle is to the individual, the more demands the other person puts on him or her. The three circles are:

1) Close relations - family members, friends, colleagues - anyone that you deal with on a personal and everyday basis.

2) Close environs - neighbours, customers in a shop, business partners. These may all pose a danger so one must act politely and friendly towards them. So  smile a lot when one meets them.

3) Unknown strangers - people of short term and one time meetings. These cannot be trusted. And I can manipulate them as much as  can get away with. Better smile, though. It will keep trouble at bay.

Yes, this is overly simplified. Still it holds a lot of truth. And keeping this in mind will help you understand why things sometimes work out differently in Thailand. Did the friendly taxi driver overcharge? You may feel that this makes him a bad person - "a cheat". Not so, he is just good at his job which he after all holds for the purpose of making money. Did the smiling shop proprietor "rip you off" on that Buddha figurine? No, it is is worth whatever he can make the customer pay ...

When hailing taxis, it is common to keep your hand horizontal, fingers facing down. Holding your hand with fingers up is considered rude. The same holds true when beckoning waiters, or anyone, do so with your palm down and fingers straight with an up and down movement. Never clap, snap your fingers, or whistle. To a Thai this is the way you call for the attention of a dog, not a human.

When visiting temples, dress conservatively (preferably in white) - women particularly should wear long skirts or trousers, have their shoulders covered, and should not wear sandals.  Many temples state as you enter that photography is not allowed.  Even if there is no sign, please be respectful and consider whether it is appropriate to be taking flash photography of a place of worship.  Also speak softly when in a temple. Even more so if monks are present worshipping!

Always remove your shoes and hat when entering temples, and do not sit with your feet towards the Buddha - sit either cross-legged, or with your feet tucked behind you.  In many Asian cultures the feet are considered the lowest, dirtiest part of the body, and the head the highest.  Hence do not point to things with your feet, hold doors open with your feet, point your feet to the Buddha images, point at or touch peoples' heads,  or under any circumstance, touch monks.

The King and the Royal family are very highly regarded in Thai society, as evidenced by the pictures and displays of His Majesty and family everywhere.  Do not say or act disrespectful in anyway towards the King or any member the Royal family, even to the extent of stomping on a coin which has been dropped and is rolling away.  All currency in Thailand bears images of the King or his past relatives-- further it is insulting to Thais to be touched by your feet.

Perhaps one of the most basics of etiquette, that is often overlooked by budget travellers is personal hygiene. Thai people are fastidious and meticulous in their personal hygene practices. As Thailand is a tropical country and it seems that many synthetic fabrics from home tend to promote odor building bacteria; showering often is essential and not just every couple of days! Also, there is no point putting on yesterdays T-shirt. So show respect and consideration, as no Thai will dare mention your lack of hygiene to you personally; it is not their way.

Throwing things before someone else is considered extremely rude.  One once threw some paper bills at a desk-- for the best of reasons - to avoid them being blown away by the draft from the open door while the clerk finished his work. He immediately frowned and said: "Do not throw, sir, you are a gentleman ...".

Do not expect Thais to adhere to the rules of your own culture. - Thais find it hard to decline a request. Instead of simply saying "no", they will tell you "Yes, but ...". "Do you have mustard?", "Yes, but ketchup" comes the waiter's answer, with a somewhat insecure smile. This means, "No sir,  do not have mustard, but  do have ketchup". Do not take it to be a sign of foolishness or incompetence. It is just another way of being polite.  As a whole, Thais consider saying "no" to a request a very uncomfortable thing to do and as such try to avoid doing so.

For similar reasons, Thais will ‘lie’ about things e.g. if asked direction to a place and they do not know. They will give false directions to avoid appearing ignorant. If asked if a temple is open or closed, they will not say they don’t know ... instead they will lie! Thus, I found I could rarely believe what they said! - Touts in major city are annoying and can be forceful. In this case it is ok to gently push them out of the way. Again, Thais dislike showing their lack of knowledge, so may give you an answer-- any answer-- to avoid looking ignorant.

The Royal Thai Police (widely seen as corrupt by Western standards) if called to the site of an incident may result in the foreigner being expected to pay for their presence. Expect the Thai person to be first believed over the 'foreigner'.