In my experience, almost all of the shops and restaurants around the Maritim in Magdeburg are very friendly and helpful, and will try to serve anyone who speaks something that vaguely resembles English or German (let's say, at least those listed on the "Around the hotel" flyer in the con book). Last year, some even changed their shift schedule to make sure there is always at least one clerk available all the times who speaks English ...
If want to be very friendly, too, I believe the most important phrases are "Bitte" (please/welcome -- "Als U Blieft" for Eindhoven
), "Danke / Vielen Dank" (Thank you / "Dank U Wel"), "Guten Tag" ("Good Afternoon" / "Gooeien Middag"), "Auf Wiedersehen" (Goodbye / "Tot Ziens"). We are guests of Magdeburg, let's behave as such