Except in the north during winter, Vietnam is generally hot, and usually very humid, so light clothes are a good idea. Silk garments are readily available here, either ready to wear or made to measure, and are comparatively cheap. Linen is produced locally, but is not good quality.
Light strong shoes are advisable, but high, narrow heels are not. If you’re visiting Ha Long Bay, walking in rocky areas and similar activities, it’s wise to wear shoes with a good tread patterns as rocks, steps, gangplanks and so on can be slippery.
If you’re visiting the north or Dalat in the winter, a pullover and/or light topcoat might be worth bringing, but cheap pullovers and woollen goods are plentiful in the markets.
It rains a lot in Vietnam, and particularly so in the summer! If you want to bring your own rainwear, it’s sensible to have material that is ‘breathable’ as the humidity build-up, and consequent sweat, means you can get wetter inside than out! If you are likely to be out in prolonged heavy rainfall designs that cover your lower half can be a great advantage. A good alternative are the thin, full-length plastic raincoats that can be bought easily and are cheap enough to be treated as disposable. Cheap umbrellas are also commonplace.
Shorts and tee-shirts are OK, but not too skimpy. It’s respectful not to wear shorts or expose lots of flesh when visiting pagodas and temples, although this is often overlooked in places heavily visited by foreigners.
Laundry services are common and cheap, although some hotels blatantly overcharge – check the prices first! Beware, though: apart from in the higher standard hotels, the washing process is likely to be enthusiastic rather than skilful, washing instructions will be ignored (they’re incomprehensible to the Vietnamese), and you may end up with an indelible laundry mark on your favourite shirt or blouse. Delicate fabrics are at considerable risk! Dry-cleaning is OK, but the same caveats apply.
You’ll definitely need to bring swimming gear, unless you’ve no intention of sunbathing or bathing. Suitable sizes for westerners are available in busy beachfront tourist areas in Vietnam, but are of poor quality and not exactly fashionable. To avoid drawing unwelcome attention and offending Vietnamese women, teeny bikinis and skimpy swimming gear should be avoided.
Have a nice Vietnam holiday!