How to get there:
- Fly: from Rio or São Paulo to Fos do Iguaçu (Brazil)
- Bus: from Fos do Iguaçu (Brazil): Brazilian side take buses to the airport (4 R$). For the Argentinian side bus in the direction of Puerto Iguazu
What to do in Iguaçu: Helicopter (Brazil), Bird Park (Brazil), Trekking (Argentina)
First of all, you should know that it is imperative to see the Iguaçu Falls on the Brazilian and Argentine side ! The two experiences are different and are unmissable. Brazilian side: Entrance fee: R$ 57 for the general rate. Discounts for students and holders of a Brazilian RNE. More details. Take the bus in the direction of the airport (R$3.20) on the following 2 avenues 
In 40 minutes you will be at the entrance of the Iguaçu Falls. On site, you can do the helicopter over the falls (about 400 R$ / person), the bird park (count 2-3 hours to walk quietly, price of 30R$ or 15R$ for students), boat at the foot of the falls, kayac … Many guides will tell you the prices make play the competition to lower the prices. You can also take a walk along the waterfalls to admire the falls, the coati (specific animals of iguaçu), butterflies or even toucans if you observe the trees well you may be able to see some of them. The coati https://www.youtube.com/watch?v=a0nJ12mXLQ0 Toucan https://www.youtube.com/watch?v=FQxhCJEt1RA Argentine side: Entrance fee: 330 Argentine Pesos (1€=16pesos approximately) Or 250 pesos with a student card, an RNE (identity card) from a Mercosur country. More details. You have to take the bus (4 R$) around 8am on the same side and on the same road where you took the bus to the Brazilian side. The bus goes in the direction of Puerto Iguazu. The bus then stops at Brazilian customs. But he certainly won't wait for you to leave. So you will have to wait for the next one with the same ticket (which can be very long) or you can take another bus always in the direction of Puerto Iguazu. Then ask the driver: "Donde esta la parada para ir a las cataratas?". It will tell you where to stop and which bus to take. The last bus costs 50 pesos or about 3 €. You will arrive on site between 10am and 11am hence the need to leave early. The Argentine side offers 3 treks. They are not difficult only they take time enjoying and walking well you will have finished everything before 16:30! 
We advise you to start with the garganta del diablo the trek in orange located at the top of the map. Then the order does not matter for the red course and the one to its left at the foot of the waterfalls. All the treks are easy and amazing don't miss them! HAVE A NICE TRIP! Iguaçu Falls on the Brazilian side: Iguazu Falls on the Argentine side:
Tips:
- For your return check-in , if you are leaving during the day, take the seats to the right of the plane ! You will have an incredible view of the Iguaçu Falls!
- Sleep on the Brazilian side and do everything by bus.
- Think carefully about the customs entered and exited especially on the Brazilian side. We almost got a fine when we left the territory by plane for Bolivia because we did not have the stamp of entry into Brazilian territory.
- Take your student cards or anything that can justify that you are a student. You will have discounts. Photos don't work!
- Make change for Argentina before leaving for the Argentine side.
- Don't forget your passport !