[gary_bernhardt]

I second this advice, having done it. I flew one-way from Seattle to Dublin in 2010 with no plan beyond the first week. 25ish cities and 4.5 months later, I flew back. You'll figure it out as you go.

But, a warning from experience: when you fly one-way to another country where you'll go through immigration, always pre-book travel OUT of that country as well, and have printed (on paper!) proof to show border control. Fortunately this doesn't apply between most European countries due to the Shengen area. Immigration is not the part of the trip where you want to wing it. Always make sure you understand the visa and border crossing rules in advance.

[splonk]

I don't recommend that people do this without a high risk tolerance, but I've talked to dozens of immigration officers without proof of onward travel (I managed to fill all the regular stamp pages on my last passport). Probably half of them didn't even ask, and most of the rest of them immediately accepted that I was going to buy some ticket out in a week or two. Maybe I got lucky, but I think "American software developer" just doesn't look like a real high risk to them, and I probably don't present myself as a backpacker who might run out of money while I'm there. I have brought printouts of savings and retirement account balances and such, but I've never had to show them. I would have been willing to buy a ticket out on the spot if necessary as well.

Weirdly, it's the land crossing to Canada that has always been most difficult for me. Once, after getting pulled aside to chat with an officer for 15 minutes or so, he eventually said, "so what you're telling me is that you're rich enough that you're not coming here to work in the oil field?" "Yes, exactly."

[gary_bernhardt]

Yeah, you can get lucky. But if you actually get denied entry and put on the next flight back, you'll wish you'd printed that flight receipt. All it takes is one officer having a bad day. (Or one who doesn't like [insert part of your identity here].)

[amacneil]

You’re right. In my experience, proof of onward travel is usually required by the airline for you to even board the flight, not by immigration officers. I don’t think I have ever had an actual immigration officer ask to see proof of onward travel.

[amacneil]

Agreed on the one way flight and immigration. Just book a separate fully refundable flight out of the country, within the required time frame (most countries it's 90 days). You pay extra for fully refundable, but you're not going to use it so it doesn't matter.

Luckily, the most skeptical country to enter as a "traveller with no plans" is the US, so if you're starting here you don't have anything to worry about. Many countries you can go through immigration without even talking to an officer these days (assuming you have proof of onward travel).

[ncpa-cpl]

Requires a passport from a developed country though :(

I've tried the kiosks in the U.S. and Mexico and always get sent to an officer.