1. You make purchases within one day in excess of a certain limit. In Singapore, this is 100 Singapore dollars, in Paris - 175 euros, in Amsterdam - 50 euros. Find out the limit in the country you are going to be available in advance - the part is listed in Russian Wikipedia; The rest must be searched for on request [ tax free refund + your country's name]. The hotel staff and the information service of large stores are also usually in the know.
All purchases in the check should be made in one shop - but if you walked through the big shopping center and bought a camera, a bag and souvenirs in different departments of different brands, it's also considered.
2. Without leaving the store, you need to issue a special check for tax refund. Usually the cashier prints out a long piece of paper into which you enter your passport details; In large stores there are separate racks (and even floors) for processing tax refunds for you.
You keep this check carefully - while buying on departure from the country, pack it in separate packages. An employee of Tax Free at airport can ask you to show the things you bought (it happens quite often, but it happens). In this case, it will be more convenient if in your suitcase packages from local stores were laid on the surface. On all things tags must be kept: so you can prove that things are new and bought right here, and you are not trying to return the tax for the shorts that they brought with them to the beach.
3. As you understand, at airport you need to find a tax refund rack. There are usually a few, and most work around the clock. You come there with all checks and purchases - it's better to register (if you're going to take these things to your luggage). Then there are three options:
A) a staff member of the Tax Free desk looks at your things, checks checks and puts on each stamp. You seal everything in an envelope, drop it into the mailbox right there and wait for a refund on the card. If you paid a card Yandex. Money, then it - that is, to your account in Yandex. Money. There is another option to take the envelope with you and go to a bank in Russia, but it's longer and not so convenient.
B) a staff member of the Tax Free desk offers you money back in cash - and if you are large, go around the airport with a bundle of currency and immediately spend it in Duty Free :) Or change to rubles when you return home
C) modern airports have all been automated, so you can not even communicate with a Tax Free employee.
For example, in Singapore, it looks like this: you go to the special terminal and you scan your passport. And then "roll" in the slot on the right cards, on which you made purchases. The terminal recognizes the purchases you made in Singapore on this card, asks you to confirm the amount, and in a couple of days the money will come to your account automatically. If the card is not recognized for some reason, you scan your check from the store - it has a bar code. In principle, the entire operation takes a couple of minutes.
This is a check after visiting the Singapore terminal. Our colleague Anya bought a suitcase, and about 6% of its value was returned to her (about 1% is taken for processing the check by the terminal).