As most people said, I use ATMs at my destination for my primary source of foreign currency. However, I hate to arrive with no money at all, so if I don’t have any from a previous trip I’ll get enough for one day at the foreign exchange booth at the airport.
In Canada the Post Office barely acts as a Post Office.
I’d certainly wonder if you handed me one, since the polymer $5s aren’t in circulation yet! 
ATMs are fine for getting more money when you are there, but it is nice to have a selection of smaller bills for the tube or whatever, which you can get from banks.
As for the black market, that can work if you know what you are doing (not good for Euros.) When we lived in the Republic of the Congo (Leopoldville back then) we got money for the Congo Republic (Brazzaville) through official channels. We took the ferry across the Congo River, had a good dinner, bought some stuff, and then my father turned his CR francs into RC francs using a guy on the street at the black market rate. We came back with more money than we left with.
I generally get some money before I go, but not much, normally from the Post Office or my bank. I always make sure I have at least a day or so’s supply of money with me, after being stranded in a small town with a broken ATM, where lots of places didn’t take cards, for two days. I’ve also been in a backpackers with a guy who triggered his bank’s fraud detection system - triggered by use in an unexpected country, as he did a side trip over a border. He was stuck with nothing until he could get it sorted out, which took a few days.
My current bank has some kind of a deal going on with quite a few other international banks, so you can use the card in their ATMs without extra charges. It’s a bit of a faff, finding the right ATM, but that’s generally what I have done while travelling.
I work for a bank, so I get a preferential rate if I exchange at my home branch. If I run out, I use an ATM, although I’d probably use a credit card if I was running low on cash.
Ordered ahead of time from the bank. I ordered it online because getting foreign currency in person can be a hassle. I don’t even know if the USPS can do this. When I got there, I would use a credit card with low foreign transaction fees to purchase directly, unless the place didn’t take CC. I think Capital One has like 0%. I personally would shy away from airport kiosks.
ATM. No fees with my card and the exchange rate is better than the airport.
Depends on the location, in general ATMs. The least ATM-prone locations I’ve visited have also been relatively long stays, so I didn’t want to be carrying from the first day the total amount I figured I’d need (which could be wrong anyway).
With regard to using ATMs, be sure to tell your bank your travel plans beforehand lest the card be disabled for suspected fraud.
I usually check to see if my bank has any kind of relationship with any bank in the country I’m going to, find one of those banks when I first arrive, and get cash from the ATM. If they don’t, I just find any bank and get cash from an ATM.
The big exception was Belize. I just took USD. Everyone took US and would take and give change in a mixture of both, or either if you asked and they had it.
ATMs are the easy answer. But we also mooch off friends and relatives (who mooch off us when they visit here).
But generally, we don’t use cash if it all possible. Credit cards work much better–their fees and exchange rates are very good.
Oh, that reminds me of something strange that happened to me when I was recently travelling overseas. Some American-English-accented guy wanted to give us two seemingly new $100 bills, but were each missing one corner. He said he couldn’t exchange them because of the damage. All my internal fraud sirens were going off, so we refused him. What kind of scam was that?
I always thought this was just common sense, but- inevitably- every single trip, one of my travel companions ends up having to borrow money because they forgot to alert their bank (and no, it’s not the same person every time :p).
BofA was my primary bank when I went to Fiji and they told me which banks there they had their little dealie with. Which was all well and good until I was trying to find the one ATM in town that was that company. Then BofA charged me an international transaction fee anyway and wouldn’t reverse it. Reminds me why I switched so Schwab, it does.
And you’re totally right about Belize-- everywhere we went, they quoted prices to us in USD. I feel like I wasted time even exchanging my money.
I assume you mean he wanted to change his two torn 100s for the equivalent US currency, yes? Yeah, internationally, I’ve learned that most places will accept USD. . . if they are pristine. They can’t be bent, torn, folded, excessively dirty, etc. Crisp, clean USD are it. I’m guessing he really couldn’t exchange them anywhere, even a bank (which I’ve heard happen).
I generally change some while in the US (possibly also at the destination, depends on where I’m going.) I will also pull from an ATM and have ordered from my bank in the past. Unfortunately, Travelex discontinued my favorite option, the Cash Passport card.
Very good point. I get hit when I travel across the same country, even. Although at least in that case it’s an automated messaging asking me to verify purchases, and doesn’t (initially) lock the card.
When I worked in a bank, a few customers asked for crisp hundreds, using that explanation. Certainly no fraud assumed in that case, but I would be more reluctant to exchange my own money in a foreign country with some random guy. I recall the bank customers were usually Filipinos visiting home for awhile.
And of course, any bank in the US should take your damaged bills if >50% intact.
Issuing traveler’s checks was a pain in the ass. I can see some benefits, but usually it was older customers asking for them.
In Japan, the only* ATMs that take American debit cards are at the post office. Japanese bank ATMs apparently don’t have networks, or anyway they don’t include American ATM networks.
This is ok, since those post office ATMs are very easy to use, they have English and other foreign language screens. You just have to plan a little more to a)find a PO and b) go when they are open.
As for small change, the first thing you buy will get you more than you would ever want. The smallest bill in Japan is 1000 yen (currently about $10). Everything smaller is coins. You’ll want to take every opportunity to get rid of your one yen coins, they accumulate like hangers. Also, most RR ticket vending machines take larger bills and give change.
*So I was told after a few failed attempts at different banks.
Roddy
Similar problem in Korea. Only the big banks will take foreign cards and big banks are hard to find outside of Seoul (or at least hard to find in the province my family lives in).
I believe any Citibank ATM in Japan will work with American cards. Although that’s nice, I am NOT giving Citibank a plug here. They are nasty little fee-chargers like most other big banks.
I recommend banking with Schwab (like a couple other people here do). Nothing like free ATM use anywhere in the world. That’s ANY bank machine at all–not just a specific network. Even that shady looking one at Joe’s Corner Liquors… 100% free. Never any bank fees, and any machine fees are refunded by Schwab.
We always buy our currency before we go at a local AMA branch (Alberta Motor Association) - I guess that would AAA to you guys. We get our travel insurance there at the same time - we don’t set foot in the US without being well-insured. 
22 years ago, I sent $5000 to my CC account before leaving, so I had that size credit balance. Then I made a cash advance at a corresponding bank. More recently, the only foreign countries I have visited (since 2001) have been the US and Barbados. Barbados has branches of my own bank (Scotiabank) so I use their ATM. For the US, I have a US bank account and use their debit card in their branches. In both cases, I bring along a few dollars, just in case.
Decades ago, this was a headache. Then I used traveler’s checks. They cost, but there really wasn’t any choice.