Another factor to keep in mind when teaching in the land of smiles is that Thai students and indeed most Thai people can be very shy and it will take a little while to break this down and develop their self confidence in the classroom. Your first lesson with them may well be the first time they have ever spoken to a native speaker. Hence, their listening and speaking skills can be very poor and the mere thought of communicating with you will have them trembling in fear. Break this fear down by being very friendly and encouraging and above all by smiling a lot. When you have managed to convince them that making a mistake is not bad and that it really is the only way to learn you will find they kick back a bit and start to enjoy the lesson.
Attire is very important.
For women, skirt and blouse. It can not be over emphasized how important your dress is. For those coming from cold European climes it may seem strange to shower twice a day and smother yourself in perfume and deodorant.