Arm yourself with a map of Hanoi with hotels so you can easily get to your accommodation from anywhere in the city.
Even if it's a map of Hanoi, you can just show the cab driver where you're staying and they'll take you to your destination.
But try to study the map of the city at least a little before you go, so you can get your bearings when you arrive.
Districts of Hanoi
There are ten in total. The district in the center of Hanoi is Badinh, home to government offices, houses and villas, and the old center is Hoan Kiem Lake. Which neighborhood in Hanoi to stay in? Usually visitors choose Hoan Kiem: there are many hotels of different price categories and a large lake. Also among the best neighborhoods to stay in Hanoi is Tay Ho, with its West Lake.
There are no dangerous neighborhoods in Hanoi, and tourists are not seriously at risk. However, in any area of the city, you should be very careful when crossing the street and beware of pickpocketing.