I can´t stand to see people coming to Prague and get ripped off one way or another. Therefore I decided to give you guys some tips to look out for, so you don´t get into unnecessary trouble.
Public transport
If you´re on a student budget and fly into Prague, the best way to get around is public transport. Compared to other major cities in Europe, Prague has a very well organized public system. From the airport you can take only the bus, no subway station yet :D You can find all the information you need on their official site http://www.dpp.cz/en/. You can buy a 30 or 90 minute ticket, which you can use to get anywhere in the city. It allows you to use the subway, trams and buses. You might even consider to buy a day or week long ticket. These you can buy at any newspaper stand or the yellow ticket vending machines.
http://www.dpp.cz/uzitecna-dopravni-schemata/
http://www.dpp.cz/uzitecna-dopravni-schemata/
Be aware, if you decide to go outside of the city by bus, there are other zones, that you have to buy separately, from the bus driver. These buses are easy to recognize. All trams are marked from 1 to anywhere below 50, from 50 upwards are the night trams. The buses start with 100, these are within the city limits. From 300 are the ones that leave the city, and from 500 upwards are the night buses.
Taxi
If you want to take a taxi, I recommend to use your Uber app, it´s very popular in Prague, locals love this service. In case you´re not familiar with it and want to really take the taxi, I can recommend these http://www.ticktack.cz/. Their fleet consists of only Audi A6. They´re affordable and you have the certainty that no one will try to rip you off. You can also use the taxi that are at the airport at all times, they shouldn´t be so bad, but I don´t trust them. I never used them.
If anyone has any questions on anything related to this, I´ll be more than happy to help.