While abroad there are many things you need to learn quickly, and how the locals work with money is a very important one. Here are five tips to help you manage a little easier:
1. Learn the number system in the local language. Pretty near all countries use a numerical system which runs on counts of ten called the decimal system we are all used too. What may be different, is how your destination country counts these ten digits ie. in English we count ten, twenty, thirty... However other languages, such as Chinese, while using the decimal system express it differently in their language ie. ten, two-ten, three-ten. Knowing these differences will help you be able to show the number on your fingers as multiples.
2. Ask other customers the price of something before asking an employee/the owner. The customer has less interest and means to obtain money from you. By asking the cashier, they can simply show on their fingers, a higher number. I've had this happen a couple times when paying for food, granted they only charged me a few extra Yuan (a few Canadian cents to a dollar extra). At this point, there are a few options, you can start a pity fight with a local over a few cents, or pay and help them out a bit. Better to pay it forward. You can also ask for the price, then use an app which converts text via photo to confirm the price. Now if you're straight up being jerked around, obviously refuse. I had a taxi driver say it'd cost me 30¥ instead of ~18¥ for a ride home one night. Just politely say no thanks and move on. It's important to note, many times if you approach a taxi and ask how much it will be. This provided them the opportunity to make up a price. Simply get in the car and express the address of your destination. If they do not turn the meter on, you're not required to pay the fare.
3. Use a photo translation app, preferably one which works offline. This avoids being dependent on widely varying internet connections or restricted services ie. google etc.
4. Negotiate. In many places around the world, prices are negotiable. Always try to get the price lowered, if they want to do business with you, merchants often will. Especially street merchants.
5. Discuss and finalize price before pulling out your money. This way, the seller can't see how much you have and push you upwards if they observe you have many funds. You can use this in the opposing direction and only display a smaller amount of funds; making such an impression of what you have available and negotiate downwards.
To my Canadian friends, it takes about 2 seconds to become used to not having to calculate taxes! Once you're some place which displays prices with taxes included, it's a dream come true!