Travelers in less trafficked areas of the world often find businesses that won't take MasterCard or Visa, much less American Express. Peru offers an extra twist: occasionally shops refuse these cards despite displaying signs advertising them.
In general, Peruvians like their soles (the currency is the nuevo sol) in small denominations: a fifty (roughly $20) is OK, but denominations of twenty and under are better to ensure merchants can make change.
That noted, Peruvians tend to put great stock in U.S. dollars, so even if an establishment doesn't take credit cards and you don't see an ATM, you may still be able to buy dinner or souvenirs. Make sure your U.S. and other foreign currency is in pristine shape -- many merchants and hotels will reject torn or overly worn bills.
6. Altitude adjustment amounts to common sense
Peru is a mountainous land, and you have to handle heights if you're going to Cuzco, Machu Picchu and other landmarks of Incan culture.
How to prepare? The easiest method is drink lots of water, get plenty of sleep and ease off the booze -- just imagine how your mother would like you to conduct your life at every elevation and you'll be fine.
You can also consume stimulating coca leafs, whether in tea or by chewing them.
7. The plumbing requires some TLC
Expect to see trashcans in bathrooms next to the toilet. While Peruvian plumbing handles your waste, it doesn't do toilet paper, which must be put in the bin next to the bowl.
Some bathrooms have signs stating this rule, others assume you know: remember and spare yourself begging for a plunger in broken Spanish.
8. The Inca Trail is genuinely difficult
Along the famed trail you'll often be reminded of the Peruvian proverb: "When the road is long, even slippers feel tight."
The Inca Trail largely consists of stone stairs -- often steep ones -- and those stone stairs weren't meant to be covered by mortals. The result is that the steps feel quite high for those who don't answer to "Kobe" or "LeBron."
If just reading this makes your knees swell, you may be in trouble.
In addition, while altitude sickness tends to be exaggerated, there'll come a moment when you're going up a hill and find that your lungs have betrayed you.
Throw in the chance of heavy rains -- test your "waterproof" gear pretrek to make sure it's just that -- and the trail can feel less like vacation than boot camp.
9. There are ways to ease your Inca pain
Depending on the company guiding you on the Trail, it's possible to get porters to carry your tent, sleeping bag, food and ... well, they'll essentially carry everything, including you, should your body completely fall to pieces.
Porters race ahead to the night's camp and assemble everything before parties arrive, then cook and serve multiple-course meals, in certain cases on white linen table clothes. The result after a hard day's walk is that you feel like you've stepped out of "Deliverance" and into "Howard's End." Speaking of porters ...
10. Porters are the toughest guys in the country
Whether you're on your own or traveling like an English lord in the colonies, you'll encounter porters on the Inca Trail. These men tend to be farmers or laborers looking to earn extra money.
They carry up to 20 kilograms (44 pounds) of gear -- the weight limit is a recent development, they used to handle positively spine-shattering loads -- and they carry it fast. Some actually run along the trail, somehow avoiding shredded ankles as they navigate uneven, wet stones just to ensure all's ready before the tourists stagger into camp.
If you feel like racing your fellow hikers, great. Do not test the porters: They're pros, and you're at best a promising amateur.