Coming to Thailand, I brought my own fifteen kilogram set of misunderstandings and preconceived notions packed neatly in my carry-on. Slowly over the past year, up to the writing of this completely non-exhaustive article, I have gathered a few bits of info that I wish I had packed.
First, it is incredibly beneficial to learn the flat-footed squat. If you are working and backpacking in South East Asia, you will find the porcelain trench in the ground at times staring up at you when you are dreaming of a nice white throne. Perhaps some yoga would be helpful to stretch the appropriate muscles, so you don't end up minding your business details in a very nitty-gritty fashion. As a side note, a bathroom with toilet paper is a rarity.
An even moreextreme rarity is one that provides hand washing soap. You can find luxurious multiple ply toilet paper and hand sanitizer in shops here, so don't be too worried. And in the end, we have all defecated on our own shoes. Don't be too embarrassed when it happens to you.
Someone told someone, who told me, “say 'yes' as much as possible.” This is definitely true when meeting Thai friends and neighbors here. I initially thought it more polite to say I have already eaten when my neighbors invited me to their table. I assumed they were asking only out of courtesy, but it turns out it is impolite to turn down an invitation to eat or drink when it is offered. Always take a bite or sip (often they offer you a sip out of their own cup, which you are to hand back) to show friendship. Conversely, if you have something to drink or eat, offer it. After sitting on his porch a few nights, a neighbor offered to drive a group of us to the hot springs on the outskirts of Surat. We said yes, and he treated us to an amazing day of scalding hot water and mud bathing. We have been good friends with that neighbor ever since.
Lastly, a sincere smile will carry you incredibly far in Thailand. I have had a few conflicts with the Thai teachers that I work with in the classroom. For instance, in Thai culture, it is not impolite to talk while someone else is talking. Thus, it is OK in a few Thai teachers' minds to teach some other material while you are conducting your English lesson. Setting the smile to stun and making eye contact, I can do one of two things that I otherwise could not. One, I get in the teacher's immediate space and overwhelm them with the volume of my voice until they give up. Two, I sit down and take a water break. Almost always, the power struggle ends quickly with them handing the class back over. The best part is that everyone walks away happy. On vacation, a smile and a few words of Thai may drop you from the tourist price to the almost-Thai price bracket. Arguing about how Thais pay less will not earn you any points, though they may begrudgingly lower it a little. But smile and be respectful, and you've had a good experience while getting a better price.