Sure, visiting Berlin, Potsdam, and Brandenburg will allow you to explore a great mix of history, culture, and modern city life. Here are some travel tips for your trip:

Best Time to Visit:
The ideal time to visit Berlin, Potsdam, and Brandenburg is during the spring (May to June) and fall (September to October), when the weather is pleasant for sightseeing.

Route and Accessibility:
Berlin has two airports, Tegel and Schonefeld, which are well connected by bus and train to the city center. Potsdam is just a short train ride from Berlin's central station (Hauptbahnhof). Brandenburg is also easily accessible from both Berlin and Potsdam by train.

Altitude and Acclimatization:
These cities lie at low altitudes, so acclimatization is not generally an issue. Always stay hydrated and take care of your health.

Accommodation and Booking:
There is a wide range of accommodation options available from budget hostels to luxury hotels in all three cities. It's recommended to book accommodations in advance to secure better deals and options.

Clothing and Essentials:
Pack according to the season of your visit. Summers are warm, so light clothing is sufficient. Winters can be quite cold, so pack heavy winter wear. Don't forget comfortable walking shoes as you'll be doing a lot of walking and exploring.

Health and Safety:
While these cities are generally safe, it's always advised to be vigilant and aware of your belongings, especially in crowded places. Also, remember to get travel insurance to cover unexpected medical expenses or travel disruptions.

Local Etiquette and Respect:
Germans are known for their discipline and punctuality. When in these cities, be respectful of their rules, regulations, and cultural norms. Learn a few German phrases as locals appreciate it when you make the effort to speak their language.