You don’t need a visa to visit Thailand as a US citizen. Thailand is very foreigner friendly country. You do need some cash, not all places take cards. Most Thai people use their phone app to pay but you won’t be able to because you won’t have a Thai bank account. Sim/data cards are easy to get at
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. Foods are plentiful and affordable. Download grab or bolt for car service, it’s more convenient and safer than taxis. Show respect to the people, the culture and the temples. Wear clothing that cover up, I’ve see too many westerners wear inappropriate clothing at temples. Thai people show respect by putting their hands together and bow. Thank you in Thai is: kop khun krap(if you are a man) kop khun ka (if you are a woman) oh and don’t drink tap water under any circumstances.