Scam-free, cheap, but a bit challenging to comprehend at first, the buses in Hanoi are relatively fast and surprisingly comfortable. Pick up a map with printed bus lines on Trang Tien, the book street near the Opera house, and spend a few minutes to identify the over 60 bus lines that zigzag through and around the capital city. Find your bus stop, wait for the bus, pay a paltry VND7,000 and off you go. If you are unfamiliar with the city, make sure to tell the mostly helpful conductor where you want to jump off.
There is a city bus that connects Noi Bai International Airport to central Hanoi. Look for buses number 7 and 17. The stop is on the right side of the airport terminal exit. Buses run every 15 to 20 minutes from 5am until 10pm. The journey costs VND7,000 per person and takes approximately one hour. You can purchase and register a monthly ticket card at one of 16 city locations including Long Bien bus terminal, Bach Khoa University and My Dinh and Giap Bat inter-province coach stations.