I lived in Berlin for two years and return frequently to take advantage of all its cultural offerings. And while it's well-serviced by efficient public transportation, the sheer size of the city, at 344 square miles, means that getting around can be quite time-consuming.
It can also be daunting given the vast transportation network and different transport options that include regional trains (S-Bahn), subways (U-Bahn), trams, and buses. One tip to remember is that trams only run in the former East Berlin, while in West Berlin, it's buses.
I've found that Google Maps and the city's BVG (Berliner Verkehrsbetriebe) public transport website or app (both available in English) offer the most clear, up-to-date transit information and show the fastest, easiest connection between stops. Depending where you're going, you may need to make connections between several different forms of transit.
After reading the above, you might be tempted to rent a car, but keep in mind that you'll have to pay for parking, whether at a street meter (which costs around 2 to 3 euros per hour) or a garage (25 to 30 euros a day). Taxis can be quite pricey (with a base rate of 3.90 euros, and 1.65 to 2.30 euros per kilometer, depending on the distance), and Uber is similarly priced.
Here's some need-to-know transportation information along with the best options for getting to and around Germany's capital.