How to take a Xe Om (motorcycle taxi)?
For getting around the Hanoi, there is nothing better than the Xe Om (motorcycle taxi) for zipping around traffic. My advice before getting on a Xe Om: (A) chose one with a good motorcycle (ie., one made by one of the 4 major motorcycle manufacturers in Vietnam - Honda, Yamaha, Suzuki, or SYM); (B) chose a middle-aged driver (too young and they may drive too fast, too old and they may not maneuver as well around Hanoi's crazy traffic); (C) chose a driver with white white eyes (this is to make sure they haven't been drinking). Witnessing collisions on the streets of Hanoi are all to common so be careful. Many streets have no traffic lights!
The price of a Xe Om ride is not rocket science. Although supposedly around 10,000VND (.60USD) per 3km I normally give 15,000VND (.90USD). That should be enough to cover travel within the city. Also, I'd advise negotiating the price first as Xe Om drivers will often ask for more than whatever you give them.