Two quick choices. You get one realistic route as a photo map, the ticket to check, and the mistake to avoid.
Put the famous palace early, then finish in the old town when your legs are slower.
Potsdam is in Berlin fare zone C. For a full day with trams inside Potsdam, check the ABC 24-hour ticket (12.90 EUR); for a simple there-and-back, compare two ABC singles (5 EUR each).
ABC ticket guide Plan my Berlin daysPlanning aid, not a live timetable; check the official app before travel. Fares and palace prices checked July 2026. Photos: Wikimedia Commons (Skshyamal, Wolfgang Staudt, Flocci Nivis, Angel Miklashevsky, Kurt Kaiser, Loewenflausch, Martin Falbisoner).