The easiest and most affordable way to travel between HND and NHN is by bus. There are several bus routes operating between HND and Hanoi, with stops at major landmarks such as the Government Palace, Hoan Kiem Lake, and Trung Cao Bridge. You can purchase bus tickets from the airport ticket office or directly through online platforms like Busway or GoPass.
Hail a taxi directly to Ninh Binh from the airport. Although easiest, this may at the same time turn out to be the most expensive. It may take anywhere from 2 up to 3 hours and will cost, in the vicinity of 400,000-500,000 VND (equivalent to |17-21 USD). Make sure to call a reputable taxi company, such as Mai Linh or Vietnam Airlines taxi, to be safe and stress-free.