Neukölln is by far the most vibrant and interesting part of Berlin right now – think Kreuzberg 10 years ago. With lively bars and excellent cheap eats on every corner, I personally wouldn’t stay anywhere else.
Things to watch out for in Berlin
Cycle hire: Berlin is the perfect city to navigate by bike. The cycle paths are wide and plentiful. There are loads of places around the city you can hire a bike from, but if you're heading there for a busy tourist weekend like Easter, make sure you book in advance. I've made this mistake before, only to discover that all the bikes were gone! There is a city-wide bike hire through Deutsche Bahn (like most major cities have now), but you need to register in advance.
Cash only: many independent cafes and restaurants don't take cards, only cash. So make sure you head there with plenty of Euros or be ready to withdraw some money regularly.
Cobbled footpaths: as a city still steeped in history, some areas still have footpaths made of small cobblestones that can be wildly uneven. They're lovely to look at but torture on anyone trying to navigate them with a bag on wheels, let alone drunkenly in heels.
Slow service: don't ever head to any independent cafes or restaurants if you're in a rush. Service is pretty relaxed in Berlin when compared to other major cities. This speed is mainly to do with the more chilled vibe, but there also seems to be half the staff. It probably keeps the prices low, so don't let it stress you out too much.
Sunday brunch: Berliners like to have a buffet-style breakfast on weekends, especially on Sundays. I find them quite overpriced and lacking in anything particularly tempting, especially if you're a little picky about what you eat. If you happen to know a good one, though, let me know!