Understanding the transport will save your day and budget to travel.
Vietnam’s transport network is continuing to improve. But the most popular is motorbike. For longer road we usually go by bus or train. Airplane nowadays is quite cheap and save the time a lot.
Walking: that’s nothing more beautiful than a walk around old town in Hanoi, to see how local people live here. Around the lake, feel fresh air, you can stop anywhere you want. Bring your flip flop and discover all small alleys here.
Bus: To go around Ha Noi you can use local bus here, cheaper than taxi but also good. Check the route on website to know which number of the bus you need to get on. Vietnam was famous about driver bus who rip off and cram foreigner (even Vietnamese) into their vehicles. But nowadays they care more about the quality. With short road, the bus is also serve you water, with air-condition. For long road, you should get experience with sleeping bus. Example to go to Sapa, there are sitting Limousine bus and sleeping bus with wifi, water, air condition. They can drop you anywhere you want.
Train: Vietnam train is stretched from Ho Chi Minh City to the Chinese border. Much of it dates back to the colonial period, though it’s gradually being upgraded. From Ha Noi, they have the train to go to Sapa, Hai phong, Ninh Binh, Thai Nguyen, … Almost the train is slower than bus, but it will be more pleasant when you can see a bit of the countryside, you’ll be involved in far fewer near-collisions with trucks, motorbikes or dogs meanwhile talking with some friendly locals.
Taxi: private but you should check the good company. Vinasun, Mailinh is my recommendation, but always check the kilometer before you pay. You can ask the hotel they can book for you with the good price.
Bike: this is one thing you must try in Vietnam. Sitting back of the bike, get close to the city and feel like the local people here. You can easy rent a bike or book a scooter tour. Even you can hire a motorbike taxi or Grab bike application (with Vietnam phone number). Check the price and location before you book, around 1$ for 4km with motorbike taxi.
Agency: so many agency around Ha Noi, check out the price to find the tour that suitable with your budget.
Security remains an important consideration. Never fall asleep with your bag by your side, and never leave belongings unattended.