There is a level of apprehension that occurs whenever I need to clear customs for the first time in a new country. It's the uncertainty that sets in about your paperwork and whether it will be accepted or if there is something wrong or you need to fill out a form or make a payment or something. And anywhere where this apprehension is likely to set in is also not going to be an English-proficient place.
When I arrived in Hungary, which is in the Schengen area, I had already cleared customs in Germany. (Well, I think it was somewhere in Germany, but it might have been Amsterdam). Either way, it's modern Europe which means no issues with US passports, does not require a visa, and is run professionally.
Congo was my first truly surreal experience. It was an overnight flight from Paris to Pointe-Noire and I landed at 05:00 local time. I stepped off the plane, which is filled with a mix of locals and oilfield employees, and enter the hot, humid environment that is Congo. With passport and letter of invitation (LOI) in hand, all I could do was stand in the slowly moving line. (A visa is obtained upon arrival, so an LOI is what gets you in). Nearby in a pocket was a vaccination book because I was told I needed proof of yellow fever vaccination to enter the country. I actually don't remember the details of interacting with the customs agent. Undoubtedly, I handed him my passport and LOI, and possibly answered a couple questions. If it had not gone smoothly, I would probably remember more. Then I had to show my vaccination book to a doctor before I could enter the baggage claim area. Then baggage claim, a veritable zoo of people and drivers holding various company signs (yes, inside the declaration area). And then they wanted to see my bags as I exited. Very well, they had their go and poke at my clothes. Undoubtedly, it was very exciting as they did what could best be described as an unenthusiastic check. Apparently, I was not smuggling a bag full of somethings. And I was in.
Gabon was very different, mostly because my mode of transport there was a bit different. From commercial jetliner into Congo to charter flight for Gabon, the whole thing had a different feel. Also, I was not entering as large a city or airport so the process had much less official feel. I was going directly from Pointe-Noire to Port Gentil, Gabon via a company charter flight and traveling on less than 24 hours notice. Clearing customs involved an LOI that was was waiting for me when I landed. I had to fill out a landing card with my previous address, my work address and my residence address. These are things you get in the habit of writing down and keeping copies with you when traveling around. This is frequently requested information in much of the world. I presented my newly minted LOI and card and was clear. Sort of. I then, for reasons I never understood, sat in the airport another hour as I think they were still trying to pull all my paperwork together. After that, the driver came back and took me directly to the immigration office in town and we sat there for about two hours (and yes, I fell asleep there waiting) while they processed a single-entry 30 day visa. And I was in. Sort of. But at least in the first time.
And what of Turkmenistan you might ask. Well, that's a good question. Given what I had read, and what information had been supplied to me, I was more apprehensive about this entry than anywhere else. Yes, Congo was very strange, but perhaps I was so eager and naive I didn't know to be concerned. For Turkmenistan, work had provided me with a very explicit multi-step process of what to do and say to clear customs. Yes, I was concerned I would screw that up. Evidently, I did not screw it up. The process, while not fast (and prompts me to think how they would handle a full plane) was steady. People already with visas on one side, LOIs on the other. I was in the latter category once again and stood in line, showed the agent my LOI and passport, moved to the other window to pay $297 (for a six month visa), and went back to the first window to collect me newly minted visa. (To note, in Congo and Gabon, I never received a visa at the airport. I only cleared customs in the airport, then turned in my passport to get a visa later on.) Then, with my fresh visa, I went to the actual customs agent and declared nothing, said I worked for my employer, and went along to collect my bags. Bags were x-rayed upon exit and I was in and here I am.