Teaching in the regular Thai program is generally seen as the least desirable teaching job in Thailand.
For most, it's just a stepping stone for a better job and few have positive things to say about the experience. While the job is relatively easy - you show up, teach your classes and go with very little paperwork or homework to mark - it can also make you feel like you are wasting your time. The short amount of time you get to spend with your students added to their low level of English makes it unsatisfying at times.
I'm quite rare in the sense that I've spent almost my entire time in Thailand (seven years) teaching in the regular program, save for a few months teaching EP. Since I live in a small southern province, there aren't too many options and my current school is so efficient at organizing my work permit and visa that I have no desire to look elsewhere.
For most though, it's a good first job to have for a term or two before looking for something more appealing. These are a few tips for the newbie teacher that I hope are useful.
Forget everything you learned in your TEFL course.
Okay, that's not entirely fair. TEFL is a good introduction to teaching but a lot of the methods don't really work in the context of a class of 45 noisy, misbehaving Matthayom students. TEFL relies on the cooperation of students, something which you won't get here. Don't spend too much time talking, get to an activity as soon as possible and if that means eliminating a few steps then so be it.
Don't force students to speak.
At the beginning, students will be shy. Young kids will sit quietly with their heads down or point at their friends. Teenagers will go to more extreme lengths to avoid speaking.
I recently taught at a technical college and the boys actually started jumping over each other to get to the door when I asked "What's your name?"
I genuinely feared some boys may try to escape by jumping out of the window so from a health and safety standpoint, it's probably best to not pressure them in the early weeks.
As time goes by, students will be more comfortable with you and hopefully less shy.
Lower your expectations.
The majority of Thai students you will encounter lack a proper foundation in the English language. The better students have a good knowledge of grammar but limited speaking skills. The worst are totally illiterate in English.
As such, most of the age-appropriate material you find in books or online will be beyond them. Keep the content of your lessons simple and take the extra time to make your own materials and worksheets.
Be a fun teacher.
One of my colleagues, a qualified teacher from England, once told me "I don't agree with this idea that learning should be fun. You can't play all the time, sometimes you have to just do the work."
I'm not disagreeing with him but the reality is, Thai kids and teachers have been conditioned to think of farang teachers more as entertainers than educators. Bear in mind also that they spend the better part of six hours a day copying off the board and reading out loud. The last thing they want to listen to is some farang droning on too much.
Don't be overly concerned about being taken seriously.
Keep in mind that you were not hired because of your amazing resume or electrifying teaching methods. You were hired because it benefits the school financially or reputation-wise to have a farang. They don't really care what you do as long as you look nice and smile sufficiently.
As I said, the general level of English is terrible and the older students get, the more self-conscious they are about their poor skills.
To mask their insecurity, many will try to be disruptive. Don't start ranting and raving as you will only look like an even more absurd figure to them. Younger kids can be managed a little more easily but teenagers will test your patience to the extreme. Your natural reaction is to assert your authority but unless you can speak Thai, they aren't going to respect you in that way.
The best way to deal with it is to go along with the chaos. Mark the lesson as a write-off and chat with the students.
Don't expect support.
Co-teachers do exist in Thailand but they aren't always reliable. I don't think there are any guidelines for Thai co-teachers on what their actual role is in class. Some show up for 5 minutes then wander off without explanation, others sit in class the whole time but are buried in paperwork and pay no attention to what's going on.
As for your lessons, all I've ever been told in 7 years is "teach conversation" and "have many activities". Ignore this vague nonsense and try whatever you want in class. If the students respond to it, keep doing it. Don't feel obligated to have students standing in front of class speaking all the time. Most aren't ready for that anyway.
In summary, don't get stressed by the job. Remember that you are merely the latest in a long line of farang teachers who have come and gone. There isn't enough time to make any real progress with students' English so just try and make it fun for them. Hopefully you will gain something from the experience which you can take in to your next job.