Travelling in Berlin
Getting around in Berlin is easy with its dense public transport system. For the more adventurous, a lot of hotels offer bicycle rent as well.
The two largest public transport hubs near the conference hotel are Alexanderplatz and Landsberger Allee S-Bahn station. The hotel is situated approximately halfway between these hubs; the closest stops are Platz der Vereinten Nationen and Klinikum im Friedrichshain. Trams M5 and M6 run between Alexanderplatz and Landsberger Allee and serve these stops; tram M8 stops there as well but does not go to Alexanderplatz.
Note that the hotel is located in a hill; Platz der Vereinten Nationen is at the lower end, while Klinikum is at the upper end. The closest U-Bahn station is Strausberger Platz (U5); from there it is a short (uphill!) walk.
Berlin Central Station, Alexanderplatz and Landsberger Allee and the hotel all lie within the "A" tarif zone of the Berlin public transport zone.
Travelling to Berlin
By car
Your average navigation system should be able to find Berlin (the one in Germany that is, not the various namesakes in the USA, South Africa or Russia). But as with all large cities find a spot for your car can be difficult and/or expensive. To find a parking garage or place try Parkopedia. Also Berlin has a low-emission zone for which you need an Umweltplakette.
By train
Berlin is linked to many place in Germany and Europe by a high-speed train network; the booking site of the Deutsche Bahn is one of the best places to look for connections and they offer cheap tickets if you book well in advance. Most trains stop at Berlin Hauptbahnhof (Central Station). From there you can take the S-Bahn (S5 or S7) to Alexanderplatz and change there for the tram.
By airplane
Berlin Tegel Airport (TXL) is the main international airport of Berlin; oddly enough it does not have a direct train or S-Bahn connection to the city but there are several BVG bus lines. The TXL Express bus runs to Alexanderplatz frequently between 7:00 and 22:00 (and presumably all through the night as well).
There is also a second airport, Berlin Schönefeld, which has more airlines flying within Europe. This airport however has a direct train connection to Landsberger Allee S-Bahn (see above), with the S9 running between Schönefeld and Pankow.
Finally, there is a chance you find a direct flight to Frankturt where a lot of intercontinental flights land. From there you can take a high-speed train (ICE) to Berlin.