I would add to some off the banking advice above... I found that parts of my bank's app and website did not work out of the US even with a VPN. I lost the ability to transfer money between banks with Zelle. Every time I called the bank to try to figure out why it was happened they didn't know why... it took a lot of work to figure it out. If you can know these things in advance its so helpful.
Find out if your American credit cards have 3D protection- its the international standard for security and most Thai apps don't seem to work if the card doesn't have it. So for example, Chase credits cards are a problem on grab but not in person.
And I completely agree with an above comment about US phone numbers. You can find out in advance if your bank requires two factors authentication for certain things. I ported my US phone number to a VOIP service. Some text messages do not come though there. Most banks/companies I have been able to figure out how to make it work but it was a painful process to sort though it. It was really convexity to keep the same US number and just transfer it to the VOIP service.
Culture shock was mentioned somewhere also- if you can learn about culture shock and reverse culture shock in advance, it can be helpful. Knowing what is normal and what to expect in the different layers of this experience is helpful in understanding your responses to things.