You may take a train from Hanoi Railway Station to Ninh Binh Railway Station. However, this is not as convenient as other means of transportation. If you are in a small group, you can take a bus or a taxi since it is not too far from Hanoi. There are regular bus which depart from the South Bus Station in Hanoi (Giap Bat Bus Station, Giai Phong Road, Hanoi, Tel: 04 3 864 1467).
Motorbike is another form of transportation, especially for those who want to explore the many landscape of Ninh Binh. You can hire a motorbike in Hanoi then drive wherever you would like. It is more convenient than bus and train since you are not depend on the schedule. Moreover, you can also save time, money and visit many places which can only be accessed by with such vehicle.
You can also get there by taxi, which is a little bit more expensive than others but it will be faster and more convenient. In addition, you can transfer to different place with less tiredness than transferring by motorbike. It do have disadvantage that is you may feel tired since you have to drive by yourself. Nevertheless, if you are adventurous, it is properly your choice.
Above are several suggested forms of transportation. You may choose from these the most suitable one for your journey.