Okay, I've been rather blessed over the last few years to have people to stay with in Europe. Berlin was such a place, but I heard that Ostel is relatively cheap, (though the price has increased), and gives an 'authentic' feeling of East Berlin under the Soviet Union. If you're looking for something eccentric, then this place offers bunkbeds galore. Or if you really want to try something kooky, then my old friend Couchsurfing is supposed to be at the height of its services. Nothing beats staying in Berlin with a local who knows the night-life like the back of their hand.
And location-wise? Again Kotti/ Kottbusser Tor, is outside of the main tourist area and has quite a lot of restaurants, parks and random entertainment to explore. It is predominantly a Turkish area, so you know what that means- 2am kebabs. Again, I stayed in Berlin for about a month, so I had enough time to pace myself. But three days should be enough to get a taste of the Berlin flavour.
Places to See:
The Reichstag (Parliament), Jewish memorial, Checkpoint Charlie (DDR Museum), Museum Island, Brandenburg Gate, Alexanderplatz, Berlin Wall, Art District (Kunsthaus Tacheles), Russian Memorial as well as all the various parks to visit. Former airport, Tempelhof Park is well worth the visit if you have extra time to spare.
Getting to and from Berlin:
Both Easyjet and Ryanair do cheap-ish flights from London Stansted or Luton to Berlin Schoenefeld, which is less than the main airports. But you have to factor in transport to and from the airport which is ₤15 as well as extra luggage for ₤30. So a small bag should suffice. I had a handbag for one month! Ryanair can do return flights from £40 excluding tax, while Easyjet is a little more expensive £65.
Berlin is well-designed to get around fairly easily. Whether you want to cycle through the town or take the overground train/tram, there's a stop everywhere. Buying tickets was a little annoying from the machine, so you need to know your destination in advance. Insiders Berlin gives a handy guide on buying tickets:
A basic zone AB ticket will cost you €2.10. The ticket is good for 2 hours and allows you to make as many changes as you need (from bus, to tram to U-bahn etc) in a 2 hour period as long as you are travelling in the same direction. In other words don’t try to treat it like a return ticket.
And Deutsche Bahn's Call-A-Bike service is a great place for renting a bicycle and the first-point of call to get a hold of one.
Luckily, a lot of people speak English, so don't be afraid to ask for help or try the Reisezentrum (Travel Centre) inside any train station. Otherwise it's a great place to stretch your legs and soak up the sights.