My final thoughts & tips on coming to Thailand.
1. If you're just coming for vacation and plan to stay at the beach or other tourist areas, dress for comfort. Bring one dressy-casual outfit if you want to go to a fancy restaurant or club. But in general a swimsuit, shorts & T-shirts will be fine, lighter colors, lighter fabrics. You will sweat. Sarongs are available on every beach for about $3-$4 US. Scarves (silk or pashmina) can be found at street markets for about the same price. Expect to pay more for a handwoven silk scarf or anything hand embroidered - from $20 & up depending on the quality. Cover your knees & shoulders when you visit a temple, and be prepared to remove your shoes when entering a home, temple or some shops.
2. If you're coming to Thailand to live and/or work, or if you will be spending time in a city like Rayong (why???) and around Thais who don't work in the tourist industry... there is a certain standard of dress expected/appreciated. Although women wear shorts cut up to their hoo-has (Usually paired with a long shirt/short dress which leaves the casual observer to wonder if they are wearing shorts at all) shoulders and cleavage are almost always covered. The only Thai women I ever see with their shoulders bare are either prostitutes or hanging out at a club.
For work remember that collared shirts are "more polite" than non-collared shirts, tucked in is more polite than hanging out, shoes with covered heels and toes are more polite than mules or sandles. While Thais have raised the humble flip-flop to a place of high fashion (beads, rhinestones, embroidery, etc), they are still not appropriate for work.
Unless you are very small you will have problems finding clothes & shoes in Thailand. There are fat Thais, and they wear clothes, so obviously it's not impossible but the range of sizes off the rack (or at the market) are shocking to someone used to American vanity sizing. I saw a pack of tank tops the other day and the large size had a chest measurement of 34 inches. I am not kidding. I can occasionally, very occasionally, find an XXL in Tesco that will fit me, but in general I'm out of luck. Bobby is unarguably slim, a size small in the states, no problem. She is able to find clothes here but, for example, the pants she bought in Bangkok were a size XL. It's a bit dispiriting.
If you're coming here to live, do your best to learn as much as you can but be realistic. It's a tough language, with five tones and sounds we don't usually use in English. If at all possible, sign up for a Thai language course either in the states or when you arrive. I did NOT like the Pimsleur learn Thai CDs. Alphabet flash cards are a good start, but require a Thai person to teach you. I've had moderately good luck just whipping out my cards at work or on a songthaew... some people will jump in and help, others are not so much interested. Fair enough.
Common Sense - If you die in Thailand you die in real life.
Because Thailand is so very different from the US it's tempting to treat it like it's not the real world. I think this makes it easier to drop your boundaries and fears and to try things you never thought you would (eating bugs, riding on the back of a stranger's motorbike). This is all fantastic fun, horizon expanding, growthfull and all that. But remember that actions still have consequences.
As amazing and dreamlike the beaches are here, if you go swimming drunk you can actually drown. You can get pregnant ... even if you're in a bungalow with no running water. And rates of STD are high here due to the sex trade (If you wouldn’t sleep with a prostitute in your country – why would you even consider doing it here?). Drug laws are strict & even enforced occasionally. You do not want to end up in a Thai prison. The embassy will not come rescue you just because you are a US citizen, the best they can do is give you a list of lawyers to call. Motorbikes are fun to race around on, but dogs (& other drivers) fly out of nowhere and the ground hurts. One of the teachers here was severely injured in a motorbike accident and will be taking home six screws in his shoulder as a souvenir from the experience.
There is a lot of fun to be had, and it's nice not to be coddled & protected to the nth degree like you are in the US. But it means you have to take responsiblity for your own safety. Best advice I've heard is - If you can't be good, be careful.
Living in Thailand has been an incredible experience and I'm very glad I came. But it's not paradise, and it helps to know what you're getting into before you get here. I hope you found this guide helpful. If there are other topics you'd like to know about, let me know and I'll see what I can do. =)