As in many places around the world renters are not always seen as customers. Although you are paying, the owner will see your stay as a privilege they are extending to you.
Owners do not see any natural wear to the house / unit as their responsibility.
Check that the refrigerator and freezer work before signing anything. I made that mistake more than once and guess what?
Learn to clean and maintain your air conditioner(s). Thai style is to let them get so dirty that they begin dumping water from the front. Owners can be reluctant to pay for the cleaning past the first time. Having repair people come in to do it for you is cheap but they often don’t do the job right, are always late and don’t always clean up after themselves.
Discuss the TM30 before signing. Be 100% certain they understand their legal responsibility to cooperate.
I had to vacate, break my lease twice in Korat. Once, there was a tremendous ant infestation going on that was not apparent at signing. When I reported the problem it was, “sorry, Thailand has insect, not like your country”. The other time my first month’s electric bill was 7000 baht for 15 days of sporadic use. “sorry, government rate, maybe you should use a fan”.
You could fight these things, better to just be very careful first.
Please contribute to the economy while we look for lots of loopholes and hurdles to make that process confusing, difficult and a constant moving target for you. If our visa officials are vague, inconsistent, subject to mood swings or grossly incompetent, be sure to see that as a language / cultural issue or as a personal shortcoming you should have sorted out before coming.
You have received many good responses. As said, remember that “maybe” applies here more than you may be used to. Provide yourself with plenty of options, backup plans and cushion for the unexpected. Your ability to stay calm and change your expectations will be tested.
Say as little as possible and smile, smile, smile. Nodding your head in agreement to everything is also helpful. These people are Bureaucrats. They adhere to rules in a haphazard way and would much rather be lying in a hammock somewhere looking at their cellphone.
Smile, be agreeable, don’t upset them. Don’t disagree about anything. Say thank you a lot and lower your head as much as possible. They can absolutely ruin your present and future travel plans based on a whim.
I understand. There may be many philanthropic groups looking for a teacher “just wanting to do good”. Perhaps a religious organization of some kind.
However, you could also just do a great job teaching in Thailand, get paid well and make lots of friends. Once you have that visa and understand the situation here in Thailand better perhaps you could seek out underprivileged students and help.
I have found that when people receive things for free or very cheaply they tend to respect the giver and the services given less. Students that pay a fair lesson fee always outperform those that do not.