Flight reservation & shuttle to Ostrava
Before you even start to do plan how to get here, thing also about the time and place of your arrival.
When you arrive during day, there is slightly more options how to get to Ostrava and dormitory. If you arrive over night, it is sometimes hard and more expensive even to get here, and there will be nobody to pick you up (though some buddies are so kind they'll do it, despite the fact they are going to skool or work at morning). Afternoon is best option.
Czech airports Prague (PRG) and Ostrava (OSR) are not only option how to reach university city. Geographically and by transport time is austrian Vienna (VIE) and polish Katowice (KTW) near too.
After you'll buy the ticket, don't forget to let know your ESN buddy about your exact arrival time to Ostrava-Svinov train station, or Ostrava main bus station (UAN), then he or she can better plan your pick up.
From Prague Airport
When you arrive at the airport, you have to take shuttle bus to the main train station, as the train is the best way how to get from Prague to Ostrava. Shuttle bus name is Airport Express.
Now just buy the ticket by them eshop. from Praha hl. n. (Prague main station) to Ostrava-Svinov. The sooner you buy the ticket, the better it is for you - with the Czech Railways (ČD) you can get better price if you buy it in advance enough, RegioJet requires reservation or you can go by LEO Express right from airport. With the Czech Railways, it depends what kind of train you take. If you take one of those more expensive (marked "SC" or "Pendolino"), your journey will probably be very comfortable. With RegioJet you travel comfortably for sure, having free hot drinks included and cold drinks and snacks.
From Ostrava Airport
The best and cheapest choice is to use public transport. For about 36 CZK (1,50 eur) you get to the main bus station in Ostrava where your Buddy will pick you up. For information about departures of buses please ask at the information desk at the airport. If you miss all connections, use personal transportation company (cheaper than taxi). Or you can use new train connection from airport to city centre.
From Vienna Airport
From airport you may choose City Airport Train or subway either, to Vienna train stations, where you can jump to direct train to Ostrava-Svinov (like this). Another choice are buses, by RegioJet for example.
From Katowice Airport
You can get straight from the Airport to Ostrava-Svinov (train station) for about 400 CZK with few companies:
Compared to other ways of travelling from Poland, this is the fastest, cheapest and the most comfortable, because it is a big car in which you get on right at the entrance of the airport and you get off just a few bus stops from your dormitory. It is also very reliable and flexible - if your flight for example lands in KTW at 6 am and their first car goes at 10, in case you are the only passenger (which might easily happen!) you can agree with them that they will arrive earlier.