If you fly business class, you can usually save by waiting to upgrade at the airport
I know it might sound strange, but I always advise everybody to purchase an economy ticket at home and upgrade it at the airport. Opting for an upgrade will drastically reduce the price of the ticket.
As soon as you purchase your economy seat, you may start receiving email deals to upgrade your ticket but don't rush. Wait until you get to the airport and ask for an upgrade at the counter.
Sometimes, if the plane is empty or you have a loyalty program with the airline, the gate agent can upgrade you to business class at no additional cost. But even if you have to pay, it's still going to be much cheaper than buying online.
Never waste money on bottled water at the airport
You can't take liquids through security, but no one said you can't take an empty bottle.
Most airports are full of water fountains, and many even have a special pump to refill bottles quickly.
The same rule applies to airport food
For some reason, people have a fear of bringing food through TSA security. But it's a great way to save money, as long as it's solid, like a sandwich.
If you're flying internationally, it's best to finish any food from your first destination before landing since some countries don't allow fresh foods through customs.
You can find better deals online than at the duty-free shop
Duty-free always attracts passengers at the airport, but the savings aren't as good as they seem. Some airlines also have duty-free catalogs onboard where you can shop in the skies. But those prices are even worse.
You can find much better deals online if you take the time to look.
It's almost never worth it to exchange money at the airport
Too often, people land at an international airport and realize they don't have the right currency. But the airport is the worst place to exchange if you want a good rate.