When you first arrive in Thailand, you'll find the way of life quite different to that you are used to in the West. The people are kind, caring and friendly, so you should not have any difficulty in enjoying their hospitality, provided you take a little time to observe the etiquette and niceties of the culture.
Traditionally, Thai people greet each other with an action called a wai, raising both hands slowly, starting with the palms down close to their bodies. The level of respect shown to the other person depends on how close you raise your hands to your head, with the closest showing the greatest respect. You should always return a wai if you are greeted with it, but you would not be expected to be first to wai. You would not return a wai to those providing a service, such as taxi drivers, hotel staff etc., or to children.
Dress up for the occasion.
When you take out your selected lady, she will expect you to show respect by dressing smartly and would certainly be offended if you wore shorts or clothing that covers your body insufficiently.
Until you know your lady sufficiently well, it is inappropriate to show your feeling for her in public. Avoid cuddles, holding hands, kissing or such like as this is not accepted in public. Take your lead from your lady and you're unlikely to offend. Understand also that, while there is quite a reputation for the sex industry in Thailand, the true culture of the country is much more strict in attitudes towards physical contact, outside of committed relationships, so you should not attempt to become intimate with a woman until after you have made a commitment.
Most Thai people are Buddhists, practising a way of life which is broadly in keeping with all religious beliefs. You should expect to wear long trousers in or at Buddhist buildings, cover your arms and remove your shoes on entry. You should also take careful note that Buddhism regards the head as sacred and you should never touch a Thai person even a child, on the head.
At the other end of the scale, the feet are considered as unclean, so you do not wear shoes in the home or in temples and tuck your legs under your body so that your feet do not face the Buddha.
The Thai Royal family is even more important to Thai people than their British equivalents, almost to the point of being regarded as deities. Take care not to show any disrespect.