I lived and worked in multiple countries for almost a decade, as a US citizen. I do freelance programming and system admin work.

I never bothered setting up an LLC or business entity. My income would all pass through for tax purposes anyway, so I operate as a sole proprietor. That requires no setup. I never had a customer balk at paying me directly. It does mean they have to file a 1099 with the IRS, but if they won’t you can still report the income. If you have employees or more complex business needs sole proprietor might not work for you, but it remains the most common form of running a business. Since 2013 I have worked through an agency, they handle billing/payment for those customers and pay me by direct deposit.

Unless you need a merchant account or have complex accounting requirements you probably don’t need a separate business bank account. You can set up separate accounts for personal and business use, to separate the transactions. I just used one account and kept track of business deductions with a spreadsheet and folder of receipts — freelancers usually don’t have a lot of deductible business expenses or things like leases, inventory, depreciating assets, etc.

I use Charles Schwab Investor Checking because they refund all ATM fees, which can add up when traveling. They also have excellent customer service, for example sending a replacement for a lost debit card to Bangkok via FedEx. I advise keeping two accounts (in case you lose a debit card) and a couple of credit cards you auto-pay. Pro tip: if your US bank ever asks if you live outside the USA, tell them no. They don’t check but the law requires them to ask, and if you say yes they will either close your account or change it to a non-resident account.

I used Traveling Mailbox to get a Washington address (no state income tax) and never had any problems. They scan your mail and you read it online. They will forward if you need that. They will deposit checks too, for a fee, though I used my mobile banking app to deposit scans of paper checks from my laptop screen.

You probably need a physical residential address in the US to open bank accounts (I used my daughter’s address) but once opened you can change the address to a mail receiving service.

A US drivers license comes in handy overseas should you need to drive or rent a car. It also establishes state residency for tax purposes. I chose Washington, Nevada works too, easy and fast to get a license. You need a residential address for the DMV to mail the license to, so family, friend, Airbnb, even a hotel.

The IRS doesn’t care where you live or what address you use as long as you file and pay. I used my Traveling Mailbox address with them.

Most people can reduce and nearly eliminate paper mail by choosing paperless banking and credit card payments. After a while I got very little important postal mail. Most of my customers paid by wire transfer or direct deposit/EFT to my US bank, or via PayPal or Transferwise. A few still used paper checks in the mail as mentioned above.

Because I manage infrastructure (cloud hosting) for multiple customers I needed a US phone number that didn’t change as I moved around. I used Google Fi for that, in a phone that supports two SIM cards. Newer iPhones have a virtual SIM and a physical SIM slot. If you stay in one place for a while a local SIM is cheaper and more useful so plan for that. I met a few nomads who had two phones, one with a US SIM, one for local access. My phone also worked great as a wifi hotspot — cellular internet service is cheap in a lot of countries, cheaper than using Fi anyway.