The people in Hanoi and in fact throughout Vietnam are very friendly and are always willing to help. Do however be cautious and well aware of your personal space at all times.
Pickpockets are a menace, and snatching of bags are common.
Never let someone you do not know watch your luggage and never accept rides from anyone other than official taxi drivers. What might be acceptable at home is not necessarily acceptable abroad. Ask questions and find out more about your city. Learn to adapt to different cultures and customs, part of your study abroad experience is to learn more about the world around you, be open and friendly. Passports with visas are required for entry into Vietnam for all foreign travelers.