All international flights arrive at Václav Havel Airport Prague. You can take:
a) Public transport
Find your transport connection using IDOS, or install the IDOS application.
Go to Connections, select 'Praha + PID', either use 'My location' or 'Letiště Praha Terminál 1' or 'Terminál 2', and as your destination, check for the nearest bus/tram/metro stop to your accommodation.
You can also use DPP, and search for your connection from 'Airport (Terminál 1)' or 'Airport (Terminál 2)' to your accommodation.
There are bus stops located just in front of the Arrivals building. You need to buy tickets in the yellow machines (press full price: 30 min / 30 CZK or 90 min / 40 CZK or 24 h / 120 CZK). After you get on a bus, you need to validate the ticket. Tickets are valid for any means of transport (bus/tram/metro/train) in Prague for the selected time. Without the validation, your ticket is invalid, and the passenger is treated as if he had no ticket.
The Honest guide video can be helpful.
From Prague airport to Hostivař Dormitory:
This route is about 60 min, therefore a ticket for 90 min is recommended. Take a bus no. 119 from Terminál 2 to the bus station Nádraží Veleslavín. Transfer to the metro A station Nádraží Veleslavín. Travel by the metro line A to the station Skalka. Go to the Skalka bus station and take the bus no. 125 to the bus station Nádraží Hostivař. Nearby station the Hostivař dormitory is located.
From Prague airport to Hvězda or Větrník Dormitory – There are 2 options:
Option 1 (about 25 min): Take a direct bus no. 191 from Terminál 2 to bus station Nad Markékou (! Request stop, you need to press a red button to inform the driver !) just in front of the Hvězda dormitory, the Větrník dormitory is located nearby.
Option 2 (more frequent bus for about 35 min): Take the bus no. 119 from Terminál 2 to the bus station Nádraží Veleslavín. Transfer to the metro A station Nádraží Veleslavín to the station Petřiny. Go to the Petřiny bus station and take the bus no. 168 to the bus station Nad Markékou. Nearby dormitories are located.
From Prague airport to Trója (17. listopadu) Dormitory:
This route is about for 60 min, therefore a ticket for 90 min is recommended. Take the bus no. 119 from Terminál 2 to the bus station Nádraží Veleslavín. Transfer to the metro A station Nádraží Veleslavín. Travel by the metro line A to the transfer station Muzeum. Transfer to the metro station Muzeum on the red line C. Travel by the metro line C to the metro station Nádraží Holešovice. Go to the Nádraží Holešovice bus station and take a bus no. 187 to the bus station Pelc Tyrolka. Nearby the Trója dormitory is located.
For those arriving to the Florenc bus terminal.
The transfer metro station Florenc (line B and line C) is close to Praha – Florenc Bus Terminal.
IMPORTANT: Because of construction work, the entrance to the Florenc metro C line station near the Florenc Bus Terminal is closed. Detailed info can be found here.
b) Taxi
This is a very comfortable way of travel, but also the most expensive one. Prices for a taxi ride from the airport into your accommodation range from 400 to 1200 CZK, depending on your destination. Airport taxi services: https://www.prg.aero/en/taxi
Better options than taxi can be Uber or Bolt.