Ha Noi is way less friendly than TP HCM. May be it was all the bombing they had.
(1)Water: Ha Noi water contains naturally occurring arsenic, either boil water or use bottled (I never use bottled in TP HCM).
(2) The police are more strict on traffic violations = even by pedestrians.
(3) Most of the 17,000 cabs are driven by crooks. Use only Mai Linh, De Luxe and Ha Noi Taxi. Taxis at the airport have no meters. Never ride a taxi where the meter is not mounted on the dash.
Always ask someone how much a ride should be; in case of dispute hold the door open and tell the cabby to call the police. The open door will stop him from 'kidnapping' you.
(4) The Ha Noi transit system is very good - check out their web pages for routes and first/last buses.
(5) Pick-pockets abound in Foreigner areas. If you think something is going on, rotate (360) on the spot.
(6) If you are being followed, either walk against the pedestrian flow or dive in to some tourist facility and wait.
(7) For some reason there are often spontaneous street fights in Ha Noi. Disappear. Fast.
(8) Ha Noi has many high security areas where Foreigners are banned. Those guns the guards use are loaded, You can get in the National Assembly, though.
(9) Ha Noi has many historical monuments; the libraries are very good for researching things Vietnamese.
(10) Ha Noi is a good town for walking. Even if you take a Mai Linh cab to an area, many things can be reached o foot. Example, the One-Pillar Pagoda area is an area dense with history and it is about a 30-minute stroll to Hoan Kiem.
If you are going to visit the mausoleum, you must dress conservatively, no cameras, etc. permitted (one of your party will have to guard your stuff outside in the plaza).
Always check to see if Uncle Ho is in town, he flies to Moscow annually to get patched up.
If someone in that area, usually with a jacket and tie, asks where you are from the answer is Mongolia. These people are guides looking for business.
(11) Nothing, but nothing, beats an early morning coffee seated alongside Hoan Kiem Lake opposite the ugly Buu Dien building, watching the locals doing their exercises.
(12) The 'trades' villages are outside Ha Noi, best seen with a tour.
(13) Don't miss the Water Puppets. Buy your tickets early, When in the theatre area, there is a tourism information centre about 100 metres to the left (as you face the theatre) which has plenty of free maps, brochures and information.
(14) Ha Noi temperate; the coldest month is February (0-10C) and heating systems not so common (but getting better). If you don't have warm clothing you can get stuff at the Russian Market.
(15) The beer is good and cheap in Ha Noi.