If you travel by plane, choose the international Berlin Brandenburg Airport.
BER Airport is connected to the rail and road network. Airport Express and regional trains run together four times an hour from station T1-2 to Berlin Central Station. In addition, the S-Bahns S9 and S45 run from T1-2 to Berlin city centre. Having arrived in Berlin, you need to take a direct train to Frankfurt/Oder.
There is a direct train connection between Berlin and Frankfurt/Oder with the so-called Regionalexpress (RE 1). The train usually departs at least twice an hour from Berlin Zoologischer Garten, Hauptbahnhof, Friedrichstraße, Alexanderplatz, Ostkreuz as well as Ostbahnhof.
Timetables and long-distance tickets are available here: https://www.vbb.de/en/tickets/.
Alternatively you can purchase your train ticket (cost approx. 10€) upon arrival at the station, either at the ticket office or at the red-white DB (Deutsche Bahn) ticket machines.
Please consider that the final destination of the train can either be Frankfurt (Oder) or Eisenhüttenstadt or Cottbus. Also, please be advised not to get off at Frankfurt (Oder)-Rosengarten station (which is one stop before the main station Frankfurt/Oder you are heading for).
If you travel via Poland you also have the possibility to arrive directly to Frankfurt/Oder by train (without a detour via Berlin). You can obtain your ticket either at the Polish railway (PKP) or at Deutsche Bahn.
Frankfurt/Oder and its Polish neighbouring town Słubice are easily accessible via motorway no. 12 (A 12).
Coming from Western, Southern or Northern Europe, your way will lead via Berlin, e.g. from southern Germany via motorway no. 9 (A 9, from Munich, France, Switzerland, Austria), via motorway no. 2 (A 2, from Cologne, Belgium, the Netherlands) or the motorway no. 24 (from Hamburg, Denmark, Sweden). When near Berlin, please follow the signposts towards the “Berlin Ring” (motorway no. 10 or A 10) and then to Frankfurt/Oder and Warsaw (motorway no. 12, A 12). Get off the motorway at the exit no. 9 (Frankfurt/Oder-Mitte) and follow the roads no. 87 / B112 to the city center (signposts “Zentrum”, “Europa-Universität” or “Slubice”).
Coming from Eastern Europe, take the Polish motorway no. 2 (A2) connecting Warsaw and Poznań with Frankfurt (Oder) and Słubice.