Ho Chi Minh City is Vietnam's commercial engine, a sprawl of motorbikes and street kitchens anchored by a compact old core of French colonial landmarks, covered markets, and the sites where the Vietnam War ended in 1975.
December to February for dry, slightly less humid weather; in any season, be out by 7am, when the parks fill with tai chi and badminton and the heat is still bearable.
Eat com tam (broken rice with a grilled lemongrass pork chop and fried egg) for breakfast, a banh mi from a busy street cart for lunch, and grilled snails and clams on Vinh Khanh food street in the old District 4 at night, washed down with ca phe sua da, iced coffee with condensed milk.
Stay in the old District 1 (Ben Thanh and Saigon wards) between Nguyen Hue and Ben Thanh Market for walking access to nearly everything, or near Bui Vien and Pham Ngu Lao only if you want the noise and the cheapest rooms.
Use Grab (car or motorbike) rather than street taxis to avoid meter games, and cross roads at a slow, steady walk without stopping: motorbikes flow around a predictable pedestrian, not a darting one.
Read more in Ho Chi Minh City Travel Guide: Saigon's Markets, War History & Street Food and Vietnam: towering karsts, lantern towns & dynamic cities.